poor customer service by management

I am very disappointed writing this story about checkers. On the 10.07.18 I went to checkers to buy electricity I gave my card to a cashier after she processed the transaction I realised that it was a wrong tender type of electricity as I use private electricity and my card has the details of purchase condition of this type. I asked for the manager her name Is charmaine who was not interested to what I wanted to explain to her about the tender used that is wrong. after few days I send my son to go buy electricity when he came back he told me that cashiers there were talking bad about us saying that me and my wife are stupid and my son Is cleaver.......today again I gave my son a previous slip for him to go but electricity to my surprise again there we go wrong tender..my wife went to checkers to try and explain this to charmaine again and she was defending what the cashier was saying..... this incident once happened at shoprite pretoria north the admin lady there she knows what customers are we were helped professionally........what ****ed me the most about this while thing I did call citiq prepaid ********** 155 they explained to me that from the store based as long as the manager identified that wrong tender was used they must sell us the right tender and send copy of the wrong tender slip to be credited back....which was something I tried to tell charmine but without given a chance I was defeated......all I want I my R160 back that I bought my electric with or the right tender cus am home with the slip of lost money. To Charmaine she must go back to her Customer centricity value u can lose 1 customer today and 300 in a year with a poor managerial s****s u gave me