Bad service

Hi im Xolisile Sithole I would like to complain about the manager in Wimpy Durban West Street. We were served with a redish milkshake it's had lot sugar and a bitter taste. Normally wimpy serve light pink strawberry milkshake. When I complained the manager was so rude he didn't want to apologize instead he kept on arguing with me. I was so disappointed with this behavior for a management level what are the employees gonna learn from him. I still want to call me and apologize for that behavior. ***