Taken advantage off ,please assist

I opened an account with Mr. Price a few years back ,last year I went to to the shop asked for my overdue balance and payed it off,late last year I'm surprised that I have a balance with them I went to the store to enquire they told me it's card fees I ask to pay it all and close the account ,they told me I can only close the account telephonically ,i called them and I was told I have a new balance again after I paid the amount at the store they say it's for a Sim card which I was given after opening my card the sales lady told me it's a courtesy Sim card which I have never used to date.i told them how can they charge me for something I have never used and I told them their sales lady told me it was a courtesy Sim I asked them to close it ,they told me they will do it and call me back ,which never done ,now I'm surprised I have a bal of R217 that time I'm unemployed got rentreched last year hence I settled my balance now this will affect my credit score and my chances of getting employment.Please assist I don't know what to do anymore at the store it's a different story when I call them it's a complete new story why are the ripping people off.