TELKOM, WORST SERVICE PROVIDER

I received a 3G modem on 5 March, I was not happy with the product, I sent through a cancellation form on 7 March, May, and still not cancelled. I get told they are awaiting for the sales department every time I call the call center. The consultants keep on taking my details and advise I will be contacted, nothing. Today I re-mailed my cancellations form after been on the phone with one of their consultants for over 20 minutes, and I am told the email address cannot be found. Worst of all Telkom keeps on debit my bank account, for a service they have not rendered. HOW LONG DOES IT TAKE TO CANCEL A SERVICE WITH TELKOM??????