Disgusted - no customer service

On 15/03/2016 my partner and i went to Ster-Kinekor in Somerset West Mall. Purchased pop-corn and coke, whiles in the cinema we discovered we were not given Coke as requested, it tasted more like diet coke or tab. After the movie we took it up with the lady that helped us and both her and the manager was so rude, neither of them listened or gave me a chance to explain! the manager tasted the coke, which was still full and returned it saying ITS COKE, whats my problem? The lady laughed to my face saying ***??? really, is that how you treat a customer, the assistant used the F-word while speaking to me and the manager did absolutely nothing to reprimand her all this while there were other customers close by. It was actually disgusting, when i got home that evening i emailed customer care to complain about the service and rude staff - to this day i have not even received an acknowledgement or an apology or feedback! We often go there, the customer service is not always up to standard but this incident was the last straw! Is it acceptable to treat customers like this? Do you patronize and embarrass customers in public? Should the manager not have handled the situation better? DISGUSTED