Deductions of expired data contract

I am trying to get Telkom to stop *****ing my money. My data contract expired. I have requested them once via call center and twice via mail to stop deductions now. But they just keep on taking my money. And Worst part is I haven't used the 3 g device for ages. Please just stop deducting! I do not have fax facilities to send letters. The deal was done via phone and now they want me to complete a form and fax it off on my costs. Stop deducting this is theft. The number is ***