The service provided was the worst, by far, in all our trips.
Receiving the car.

First: they provide only a land phone number to call when arrived to the pickup point, reachable only if you have minutes in your mobile plan. The standard SIM plan for any international traveler does not include minutes. A WhatsApp number would facilitate the experience for the client.
Second: they do not allow a freshly issued digital international drivers license. That is absurd, the reservation is made online.
I guess the additional amount they charge clients is well received.
Third: the representative, after charging an extra insurance (tires and glass-we already had a full insurance, having or not an international drivers license won t make a difference regarding the care of tires and glass by any customer), refused to revise the car before delivering it to us. This is a basic step of ANY car rental process.
Fourth: the representative commented that the tank was not full, and that we would need to return it approximately at the same level. Calculating a gas level in a car is not easy, at it is zero professional to deliver one to customers in that condition, leaving no choice but to fill the tank (more on that later).
Fifth: no additional assistance was provided: the car was received inside the garage, with another almost completely blocking the exit. No explanation on how to use the navigator (they also charge an additional fee for a preinstalled feature of the car).

Sixth: we reserved a small car, a Fiat 500. Small Tuscan roads, and also beautiful countryside, made the choice natural. We received a bigger car, no real upgrade, no soul. It was a big disappointment.

Returning the car:
First: Surprise, at the returning stage, they actually do a revision. There was a light bulb burned, not detected at the initial delivery. One of the staff members told us: WE HAVE A PROBLEM. I think they as a company use this method of no revision at the initial delivery to charge on the insurance companies the usual maintenance costs of cars, arguing the customers were responsible for the damages.

Second: the car was returned with approximately the same amount of gas. Surprise, they do not accept anything approximated as the first representative told us, only the exact same level. It is not customers responsibility to calculate the exact amount of gas a car should have, it is the agency responsibility to deliver it full, and we as users return it full. There is no science in that, it is a basic condition on rentals. Since exact level is almost impossible to calculate, we had to go back to the service station, fill the tank, and return to the office, expending additional time, and money that is pure profit for them, due to poor internal processes.

Third: they charge the same amount for 24-hour rentals and less than 24-hour rentals. However, if a client selects a return hour shorter than 24 hours, they charge penalties if it is not met, even if they charge the same for 24 hours. That is absolutely ridiculous. For any car rental, the minimum is 24 hours, independently from whatever the client indicated as possible return time. In a foreign country, it is not easy to calculate travel time in route, so having the rental in days, instead of hours is basic.

Fourth: Any decent car rental offers the possibility to the client to return the car in absentia, specially at the airport, leaving it in a special parking. They do not offer that service.

Fifth: The staff told the angry morning customer that the security deposit was going to be released within 48 hours. They told us the same. 2 weeks later the retention remained in my account. I had to contact my bank to request the removal due to their policy of doing nothing for a customer.

In summary, the service provided was terrible, we had to expend more than 100% in addition to the original amount, the treatment of the staff felt like they were bandits trying to squeeze the last possible dollar out of clients, and we even cancel an additional car reservation -at least not with them-, not to risk suffering a second time this time of treatment.

If there was a zero l would have given that. Worse car hire company l have used in 42 years of hiring cars. Hired them through Booking.com who should know better.
They are not on the Heathrow perimeter road, but 10km from T5 20mins away. Multiple serious issues with this company 1) l missed my return flight as it took them 1.5hrs to process my clean car return. Will cost me a fortune in rebooking flights, lost flight, taxis etc.
2) Minibus is infrequent 45-60 min wait.
3) Like many other reviews and other customers there today, l found out later that they scammed me for an additional £400 for using a debit card (although l had a credit card on my phone) saying it was insurance, although l already had private car hire insurance.
Other customers today were saying they had same problem, and if they did not provide what Surprice wanted. They would not release the car and they would loose what they had already paid.
4) The mini bus collection was free but they charged £10 to drop you back at the terminal, not mentioned.
5) On arrival at T5 to collect the car they said they did not have minibus available, and they told me to take a public bus to T4 and get a Minibus from there. It all from first calling them it took me 2.75hrs to get a car.
6) Don't believe what type of cars they advertise, they will only give you a basic Kia, not full with petrol.
This company should not be allowed to trade, their practices anppear illegal if not they are misleading on purpose and very dubious, please don't be scammed, use a quality car hire company. So many unhappy people at the car pick up and return, please make sure you are not one of them. Also check out TrustPilots 87% 1 star rating of Surprice Heathrow.

Summation of my horrible experience with SurPrice/Auto One:
• Charged my credit card an exorbitant deposit of EUR900.00
• I had not one, but two flat tires in one day! The first tire (left front driver's side) blew while I was driving on a busy motorway. I had to stop immediately to prevent losing control of the vehicle and causing a serious accident. I had to change the tire on a narrow shoulder of the motorway, risking my life doing so. No emergency equipment available in the vehicle (warning triangles, flairs, etc.). The second tire (right front passenger side) blew while driving to Pisa to return the car. The spare was already used so we were stranded on the side of another busy motorway.
• SurPrice/Auto One in Pisa were contacted several times and refused to help me.
• I resorted in contacting 211 (Italian version of 911) who kindly assisted me and put me in contact with an English speaking person at Italian Emergency Roadside Assistance.
• I was met by a tow truck and driven to Montopoli, Italy where the car was to be repaired.
• I had to pay 140.00 EUR cash to a friend of the tow truck driver to get us back to SurPrice/Auto One office in Pisa (not to mention taking a train from Pisa to Lucca where I was staying).
• Surprice/Auto One charged my credit card $786.00 after the fact claiming all of this was my fault.
• Surprice/Auto One again charged my credit card 60.00EUR 17 days later with a follow-up email accusing me of a traffic violation. I was never stopped nor issued a ticket during my time in Italy. My credit card company flagged the charge as fraud and denied it thankfully.
This is a shady and dishonest company with unethical business practices. They have defective and shoddy vehicles that are meant to break down so as to charge exorbitant repair fees to replace this junk (hence the high deposit held on credit cards). The cost breakdown of my $786.00 was related to EUR 400 "Damage Charge" (very vague), EUR 26.00 refueling, EUR 25.00 penalty for not refueling (as if this was possible given the circumstances) and EUR 205.00 for the tow truck. The vehicle was a Lancia Ypsilon with worn-out used tires. A new tire typically costs 90.00 EUR for this type of vehicle.

Italian authorities really need to investigate this company and put them out of business.