Terrible service

I have an overdraft account with FNB that has a debit order set up going off my account monthly with MBD, this month when I checked my accounts the debit went off on the 29 December however this has not been allocated to the overdraft account, i contacted MBD and they advised that they last debited in October and the account is no longer with them, there has still been debits from MBD to date and now not sure where the funds are being allocated too as nothing reflects on the overdraft account and numerous agents keep telling me it is still to reflect one informed me it will reflect on MOnday when i called in on friday the 02-01 and today the 06-01. I was informed it will reflect on Friday. I need clear answers as to what is happening with this account as a matter of urgency.