Vodacom cancellation issues

I have emailed and requested conversion of my mobile account to pay as you go as I have left SA. Contract expired 31 October. Sent emails to request the same, received a response for further information which was sent and have heard nothing since. Meanwhile, vodacom continues to debit my account for over R1800 a month. Signing up is easy; they send you from pillar to post to cancel. Pathetic, underhand service from Vodacom. Sorely disappointed.