after i cancelled they start deducting from my acc

I cancelled my contract only after having it for 2 months. They haven't deducted for over 3 months now. So all of a sudden they deduct the monies last month and now this month and not even on the date we agreed upon. The money that was in my account was for another debit order. So now my debit bounced for 2 months now and have incurred extra expenses not talking about what it wil reflect on my payment history. So I would like to cancel this again and have my money sent back to my account which they debited.