shocking service

Adega midrand.. we use to love going here and enjoying the food. Tonight we were very disappointed.. not only did we have to wait a very long time for drinks and a meal -over 20 min for a drink- when the food arrived it was not up to par..the meat abd seafood was overcooked making the calamari tough and the meat dry.. when we got to paying the bill - we wanted to use a gift voucher only to be told by the manager that it was not signed by head office. How is it my responsibility to ensure a gift voucher issued has a signature on when we pointed this out to the manager and said surely you can see it has a voucher number and you can validate it with hq afterwards he said that's not really his responsibility. Further when we mentioned that he will not accommodate us he said yes he will not. This is poor customer service and I would not be returning to this restaurant. It is very sad to know customer service and satisfaction means so little to this business.. what happened to putting the customer first and saying the customer is always right.