Cancelled Vodacom Contract - still taking money via debit order

Hi, I phoned your call center in January and requested to cancel my contract with Vodacom. They confirmed via the phone that it was cancelled (as I have not upgraded at all) - the last debit order was supposed to come off end Jan but now it is 1 March and another debit order has come off. When I call, the call center says that it was cancelled and then do nothing to rectify the issue. By law I cancelled my contract, it should be recorded on your system in Jan and you are *****ing money from me by continuing the debit order. I also can't get anyone at Vodacom to sort this out as I am overseas and not currently in SA.