Wimpy Constantia

My sister and I went out for breakfast at Wimpy Constantia and the service we have received was not friendly. I even asked to speak to a manager there and I wasn't certain if indeed it was a manager because while I was complaining about my waitresses behavior which was concerning. The waitress took our order and she swapped the food around and I wasn't aware that I was eating a Burger that has avo whereas that burger was meant for my sister, she the waitress, didn't even come to check if we needed anything else and continued with her life. So I was informing the manager of this behavior and the lady joined the conversation and said " She works with a lot of customers " it's not her fault for swapping the meals. What also threw me off was when she was suppose to take a payment of R287 and she then entered R387 and I had already made the payment so if I didn't notice she wasn't going to say anything. This is all happening in front of the manager?I understand she is new but what made her comfortable to tell me she works with a lot of customers instead of just saying sorry? The customer service is poor!!