Contract cancellation issues

Been a subscriber for nearly 20 years.

I have recently immigrated and have requested my contract to be cancelled for months already. I am currently still getting debited on a monthly basis by MTN even though I have also requested that the debit order be cancelled.

I have sent numerous emails requesting the cancellation of contract and debit order but just get replies stating to call the 135 bumber. Which cannot be done from a country outside if South Africa. This has been going on since June 2021