Terrible service. I personally think they are a scam.
After ordering 5 items, 2 of which were incomplete and one was missing, and after waiting for the completion of the order which never arrived for another two weeks, I returned the package to the company after getting in touch and explaining what the problem was.
After another 3 weeks they said they never received my package with the returns and refused to refund my money.
I had to contact Royal Mail with my postage information and receipt and they have told me that is very unusual and unlikely that would happen. They have covered some of the cost although I do firmly believe, just like Royal Mail that Zulily have just taken advantage of the situation.
Just do not use them. They are terrible.