MWEB service cancellation.

Hi All, After a long frustrating battle, MWEB acknowledged cancellation of my monthly subscription for data services (5GB) package, this was on 28th November. On 30th November my service was terminated. I received an invoice for December which was paid, presuming this to be one moths cancellation fee. I received another invoice end Dec and debit order took another monthly installment, even though I had cancelled the debit order with my bank in early December. We are not talking big bucks here, but a principal. Will have to try and get some resolve from MWEB but I suspect this is going to be another uphill battle to get them stop invoicing and taking my hard earned bucks.