If you have an existing reservation and cannot get a hold of anyone on the phone, call back and enter #2 for a "new booking" and you will speak with the sales team. They have all the same information and will pick up the phone immediately if they think you are making a new booking. Don't let them "transfer you to the correct department", because they probably have the information you need.
Or create a new (fake) booking quote online and they will call you back right away. They are very good about getting you booked and getting your money, but not good at answering the phone for existing bookings.
The problem with their customer service is that there are two different departments, and the wait times are vastly different. The difference being 90+ minutes on hold and becoming very upset with them, or having someone answer within 2 minutes and giving you the info you need. If they could be as efficient and respondent with handling existing customers as they are with potential customers, review scores would be much better. Hopefully they can sort this out.