Apparantly cancelled contract but still deducting debit order

After a complaint on HelloPeter (contract expiry not processed after numerous requests), Vodacom has agreed on 8 September to convert my contract to prepaid. This was confirmed by email, after which I wrote a very positive reponce to Vodacom, however that was short lived as the debit orders are still being run by Vodacom resulting in financial loss to me. Why is it so difficult to get a very basic customer request right??