Spar 1a

I went to Spar Nina Park Pretoria North. I gave the cashier 1 x R50 2 x R20 notes the amount owed was R77.90 I then said wait I have change. I gave her the R7.90. She took it and put it into the register without giving me back the 1 x R20. She said according to her she does not owe me the R20. management looked at the footage where you can't even see the notes correctly stating there where only one R20 note insinuating that I'm lying. they do not want to check the register. I told them if they count the register there will be R20 extra in it. That R20 is my food on my table. and they can just lie again tomorrow stating there were no R20 extra. I want my money back!