Disgusting service

So we received a groupon voucher from a friend because she didn't have time to use it . I usually don't buy groupon vouchers because of the service we get when they see the voucher . We went to Zanzibar restaurant at the Westwood mall . We asked our friend if we need to pre book and she said no she never ever booked with her other vouchers. So we went to Westwood as we entered the restaurant the person standing at the entrance said something about the voucher to the waiters , before she even greeted us she said did u make a reservation and who's name is it under. So my fiancé said to her we didn't know that we had to make a reservation and we apologize but can't you guys a comparator us because you guys are not busy . She immediately wanted to call the manager. She knew that the manager would turn us away . We called later that evening to complain to the manager and the manager said that she had redeemed the voucher yet she had not even seen us. She was the most rude and ill mannered person I've ever spoken to . We asked for her name and last name . She then asked if we want her identify number as well. I will never recommend this place to anyone . We dine out a lot and we don't ever have problems anywhere . Really disappointed .