Very disappointing service from MTN

Really unhappy with MTN,

I took out a month to month internet package with MTN, returned and cancelled this 'contract' on the 30th Of September 2024, however the case was only logged as returned in December 2024 with an outstanding balance of R500. Mind you, when I returned the device to the store, I had to pay a cancellation fee - which I did. The following month I received another bill, which I queried and eventually had to pay.

IT IS NOW 2 years later and this account has not been closed and I have been requesting for a letter of closure