Still deducting debit orders policy cancelled

Cancelled insurance policy last month via mail, went to the bank and cancelled debit order also to make sure from our side that all was done to make sure that premiums wont go off. well they still tried to deduct money , we called and they told us it wasn't cancelled , so we we cancelled again, the guy insured us they wont try to take premiums, what a joke they are still trying to deduct , took out all of our money out of account, now we get unpaid fees from the bank for debits unpaid all the time, bank cant help because Hollard is changing the reference numbers all the time, they are so rude, and are robbing is with banking fees, at the end the unpaid fees are going to be more than the premiums , bad service, telling clients they wont deduct for a policy that is cancelled and until now they try everyday getting unpaid reports, already at new insurance company , cat use my bank account and the banking unpaid's are killing me, are Hollard going to cover my banking fees for them not doing what was requested a month ago? Imagine how pathetic the service will be when you need to submit a claim..