FNB ..... No help what so ever!!!

A debit order has been linked to my account. In March I received a SMS from FNB asking if I had added a new debit order. I immediately rep**** no and the debit order was stopped and refunded. Now for 2 months this debit order still takes funds. FNB says they cannot help to stop the debit order or refund me. Why could they stop and refund me the first time, but now they can't? The service provider that is "*****ing" my money does not answer their phones or reply to my mails? This is absolutely ridiculous.