Paid up letter.

I have been waiting for a paid-up letter for almost 12 months, I paid off my account in full for R1960.18 which was debited from my account on the 20th of December 2019, I asked for a paid-up letter and was advised it would take up to 14 business days, I called in numerous times and was told it would be sent it is almost a year later and still nothing, this is very unprofessional, ontop of this bad service I got a letter from the company saying they would send in for collection which I do not understand as this was paid in full, it has not been updated a year later, what kind of business are you running if you cannot follow a simple request? Please fix this