ill treated

I have a bank account with FNB , RCS has been debiting from my account since February this time around a disaster happened RCS decided to debit on the 28th and it returned unpaid and I incurred charges from my bank then on the 30th July I received another sms confirming that a payment has been made to RCS from FNB and looking at my bank balance it did correspond funny when I call the bank to confirm they say there is nothing like that and RCS tells me that I am on arrears how I don't understand their payments went through as per normal. RCS side I called last Thursday to confirm the debit order date since it looked like they debited on the wrong date for July immediately after the changes I then got notified that I am owing yet payment was made for July I don't understand where is the loyalty in this whole thing I don't miss my payments at all no matter what.