Incorrect billing & incorrect termination date!!!!

I keep on getting unnecessary calls and WhatsApp messages that I have an amount outstanding. My rain contract was cancelled more than 5 years ago so I don't understand why your records would show that I only cancelled last year. That is your internal system issues that you need to resolve however I am not going to pay for whatever you claiming I need to pay for, I have logged several requests and only today for the first time someone is actually calling me back regarding this. Can this matter be attended to and resolved coz I am its very irritating.