Debit order despite cancellation in cooling off period

In February I was contacted by Mobile Talk and offered what seemed to be a great deal with Telkom Mobile. The mobile wifi router arrived on 22 February and following activation on 26 February, did not work. I immediately gave notice of cancellation. RAM was contracted to collect the device from me. Despite notifying Mobile Talk when I would not be available, RAM attempted to collect. Several arrangements were made and RAM failed to arrive as agreed. This continued until end of March when I escalated this matter in Mobile Talk. After 3 escalations, finally RAM collected the device as agreed on 15 April. Telkom Mobile debited me in March and despite return of the device I was debited again today (26 April). Mobile Talk fails to respond to any of my emails regarding cancellation of debit order. Telkom Mobile number 08180 either does not work or if I get transferred to it by Telkom Insurance, it cuts out. There is no email address for me to contact Telkom Mobile. My bank has advised me that there will be a fee to reverse the debit order and they cannot guarantee that the vendor will not debit my account with a different reference. My only option appears to be to cancel my bank account and start afresh. My advice to any customer considering doing business with Telkom Mobile or Mobile Talk would be to run for the hills. If I could give them a 0 rating I would.