Lack of customer care & service skills

We have been loyal regular Nandos customers but today was the worst experience yet. We order food, food came, we asked the waiter for extra sauce he comes back with a little sauce added, so we ask for more sauce and advised we will pay for the extra sauce the waiter comes back and says no the manager said it’s enough. Firstly the customer is always right and who is anyone to say what’s enough if as a customer you fitting the bill? The manager flings the customer care card and says call for your refund but refuses to give us the refund. I’m absolutely disgusted and disappointed in the treatment received, honestly would never go back to this Nandos branch as it is not the first time and the staff need training as they do not know how to resolve costumer related problems.