Customer service!!!

OUpon paying our bill which my friend and I read the total to be R437. We each decided to pay in R250 which added together left R63 tip. As we leaving the restaurant the waitress named Candice approaches my friend and gives her change in coins and says to her u can give this to the car guard he needs it more than I do. We were both confused as to what was going on so eventually after back and forth conversation. The waitress points out to us that the bill was actually R487. So we explained to her that it was an honest mistake and that we both had read the bill to be R437. Never the less we paid in the difference for her tip. What I am shocked at is the attitude this waitress had with us and nerve of her returning the change to us and telling us that the car guard needed the money more than she did. She could of handled the situation in a much more decent and professional manner by simply asking us if we are sure that that was the correct amount we wanted to pay we would of re-looked at the bill and realised that we were short on tip. Never in my life have I ever met a waiter with such nerve and attitude and never again will I EVER go to Q bar if this is how I'm going to be treated