Cancellation Process Issue

I'm trying to cancel my mobile contract and the call center can't assist. They only tell my to send the cancellation form to ********** but when I do I don't get any auto reply saying they received my request or any reference number. When you phone telkom mobile they can't even tell me if they received it. Their advice is to wait a month and see what happens. This is not acceptable! They're forcing me now to put in a stop order on my debit order for when the thing is supposed to be cancel. That's the only way I seem to get their attention.