RCS does not close the account instead they charge you more money

I paid up my RCS on 02 April 2019 at Game stores, the guy that assisted me called RCS so that i can stop my account..when i called them I specifically told the lady that assisted me to stop the card because when i checked RCS reviews I found out that they never close the account and they end up charging you more money. This morning they sent me an email stating that i have not been paying my account and im overdue for R128, im sure this has dented my credit record which i have been working so hard to clear. Im really hurt by this.