Home Loan debit order date not changed.

FNB has been my nightmare in the past 2 months. I called them to change debit order date for my home loan and I told that this has been done, today, they debited my account. Who is going to pay for the unpaid debit orders? This is totally unacceptable, can some listen to the call I made to change the debit order and tell why was I told a lie that this has been changed?