Deducting money months aftr contract was cancelled

I cancelled my contract in November and had to pay my last subscription in December which was done. I phoned the call centre in December again to confirm that I cancelled - They confirmed it on their system. Deduction went off in January but from February Virgin Mobile started deducting money from my bank account again . I went in to the bank an cancelled my debit order and reversed the money but Virgin Mobile is still deducting money from my account. I went the Virgin Mobile website and ask that someone must come back to me regarding this matter and I am still waiting.