Wrong Debit Date

Miway debited me before the agreed debit date, and they are now sending me communication that i will not be covered. I have tried countless times to contact them but to avail. When i do go through they just take my number and say they will call me back. I really do not understand why i should be spending money and time to fix their problem but they do not seem to be bothered. My fear is that along the line when i want to claim they will say there was a certain month i did not pay, the bank also charged me interest and this is also depreciating my credit score.