Bad Attitude and charging for a piece of lemon

Wimpy Vaal 1 stop east N3 R145.60 paid 13:35.24 We stopped there for breakfast on our way to the Drakensberg on 7 Feb 2018 about 12h30 Had a meal etc. and asked for water to take our daily vitamins. Guy asked me ice and lemon and we said yes. On paying the bill a saw a charge of R1 which they said was for the lemon with the water. When I said I was not going to pay for th lemon, they called the manager who asked me why. I told her I have never heard of paying for a piece of lemon anywhere. She said that seeing that I was not told she would not charge me but made it very clear to me that should I eat there again I WOULD pay. I asked if this was Wimpy policy and she rep**** they charge at her Wimpy. So firstly please advise if your franchisees can make their own rules. Secondly it’s not on the menu and the manger was rude. Sadly last year at the same stop the remote jammers emptied my car of laptop and 2 phones so the place seems not a good place for us.