MNT . contract not cancelled

I send a cancellation e mail to MTN for cell nr *** on 16 August 2020. I got a email back to say that they have received the e mail and that I still will be billed for the month. I went into there offices at Walmer Park Port Elizabeth and they confirmed that the cancellation was received I realised on 1 November that they are still billing me for the contract. I send another e mail to query. I got a e mail back to say that they will investigate. I send another e mail today. I tried phoning the customer care number 135 as per there website. it does not even ring I have now requested them to phone me on ***

This is unacceptable