Being billed for random services

We had the 1TB business internet (R999 per month) from November 2020 to August 2023. We cancelled this account after 3 years due to MTN data services being unreliable. As far as our records show, the R999 was fully paid up and we cancelled as per the contract. This was a sim only deal anyway.

nevertheless, on 10 August 2023, we receive a "final notice" letter with a RANDOM amount of R519 owing. We disputed this as an error and ignored it. Since then the account has racked up roughly R107 per month for services we DONT WANT and NEVER ASKED FOR, nor have ever used.

I have tried numerous times phoning in to try and rectify this issue to no avail being told it is with the "collections dept".

All we ask is that the account we wanted to terminate back in August 2023, is terminated.