Fix your incompetence

First of all I pay my account every month, and in September you decided to debit me on the 24th, of which will decline coz I only get paid on the 25th. The declined debit I paid for it in bank charges, a 100 bucks. Then you also charged me for that unpaid, and you debited double my instalment just the following day. How can I pay so much charges for your own incompetence? I want this resolved coz there's many other month coming where I'll be paid on Saturdays and I don't want a repeat. I been asking for you to give me back my one instalment back for a month now, if I don't get help I'll start reversing it myself.