Cancellation is impossible after contract has ended - Telkom is a very ************* company!

Cancellation is extremely difficult. I have followed the process by sending required cancellation documents 5 times to the email address ********** but thee just keep charging me. I called, they said send the docs again to the email address. The last time I sent the email it bounced back saying "The recipient's mailbox is full and can't accept new messages at this stage." This is HIGHLY ANNOYING and a complete waste of time and money.