Standard bank messed up my credit score!

So I've had a loan from standard bank which has been debited from my account every single month. This month (April) I see that I have a default on my credit score because of a late payment. After receiving multiple calls from collections agencies, I advised that my bank records show that my payments are up to date and there was no late payment. Being promised by multiple consultants in customer services that they will have it removed from my records, I find that it's still there. Nothing has been done to correct this even though all of those consultants have confirmed that it was an error on their system. My credit score is now damaged because of their negligence and nobody is doing anything to fix it! I am highly disappointed as I am in the process of applying for a home loan but the result will be unsuccessful due to the neglect of customer service and their systems!

This is utterly disgusting and I now have to bare the consequences of a stupid messed up system that's not being followed by Standard bank staff!