BAD SERVIRCE NETSTAR

I have stopped my contract 1 year ago as I have sold my car and relocated to Zambia. For moths I had to reverse the debit order as NETSTAR!!!!! keeps submitting it. I even got a cancellation letter from them. It went good for moths and this month again they have put in a debit order, KEEP AWAY FROM THEM they are *****'s!!!!!! My account ***