Overcharge rude manager

I took my 80 year old momtoSpur in Graaf Reinette. I ordered drinks, mine was incorrect and they came to say they had no diet cooldrink only coke zero from tap. We ordered food. I POINTED TO THE MENU ITEM. Wings and riblets. This is for my mom. The food came we started eating, I called the waiter and said the food looks like a big portion she needs to make sure it is the one I asked for the wings and riblets. We kept eating she then came back and said no it is wings and ribs. I said but it is not what I ordered. She said then she has to take it back. Now after a 10hour drive and my 80year old mom already eating she wants to take the food and then she must wait while we all keep eating?? I SAID BUT THIS IS NOT HER MISTAKE IT IS YOURS, SHE STARTED EATING ALREADY. She left. When the bill comes the charge wings and ribs, not wings and riblets. I explained it was their mistake the manager (who said her name was Monessa )comes and says you will pay what you ate. She did not listen to me she just heard the waiter side and came to say I will pay the order cause my mom ate it. Even if the order was incorrect which by the way you would not know because there are no image on the menu for wings and riblets, then tough you pay the incorrect order? My 80 year old mom was embarrassed and what was to be a good supper left a bad taste. I worked at Spur when I was young, we never treated people so cold and hard, when the mistake was ours we apologised and fixed the bill. Especially for children and senior citizens, WHAT HAPPENED TO THE SPUR TO HAVE MANAGERS BE SO AROGANT AND COLD TO PEOPLE LIKE MY MOM. My husband was right when he made a comment that it is no wonder they are so quiet. It is appalling and I think Monessa needs serous training in customer service and should not work with fragile people at all.