FRUSTRATING!!!!! DEBIT ORDER KEEPS GOING OFF!!!!

Account was paid up on 26 March 2015 still debit order went off as normal end March, we requested a refund and had so submit banking details/statement est. they assured us it was cancelled but at end off April still the debit order went off AGAIN and once again we had to phone in and cancel and they confirmed it on email that it was cancelled but by End May the debit order went off AGAIN!!! This is sooooo frustrating we had to phone again and being pushed around from one dept to the next and still nothing is happening how many times does one have to cancel it before someone actually does their work and gets it done because ones again end June another payment/debit order went through and this is B***S*** and now we have to submit banking statement AGAIN OVER AND OVER AND OVER AGAIN!!!! for What????? I'm a business man and cannot take off as I pleases due to your negligence.... when you speak to the secretaries they refuse to put you trough to a manager WHEN WILL THIS STOP?????