Impossible to cancel internet data subscription

I have contacted Telkom numerous times now to cancel my Telkom data package without success. Why should a customer wait 50 min (maybe longer as I have not been successful in finding an operator) each time for an operator to attend to his requests. My land phone is broken and therefore I have to try and cancel the line via my cellphone which obviously costs me a lot of money. I have also sent an email to the support centre without success. This is absolutely ridiculous.