Paid my account in full and still get charged interest, STAY AWAY FROM RCS,

You guys are a bunch of ******. I paid my account in full as per my app and it showed zero balance, Now I see you charging me R48.60 on a zero balance. That is not on. When I pay any of my account TFG or Truworths, that is the end of the story, you guys tell me that I have to call in for a settlement amount, what the hell is the point of your app if it shows you that is the amount you owe, you pay it in full and then get charged interest on a zero balance, You guys are a bunch of ****** I am going to close my account if you cannot sort this out and will never ever take an account with you guys.