Denied good credit because of standard bank!

I've had the worst experience with Standard Bank not updating their files in regards to a personal loan. I settled a loan, received a paid up letter only to check my credit report and find that not only was the information about completing payment updated but that the loan had accumulated interest. So for three whole months my credit score has been badly affected not because of my inconsistency or failure to pay but THEIR slack! I cannot apply for further loans because of this.

Please rectify this urgently.