Company over charging me

I have been paying my account each month since I have been on maternity leave,double payment each month but the company still adds on interest as if I am not paying. I want to take it up with ombudsman because I cant continue paying them and they just keep adding interest as if I am not paying.i am even paying more than my monthly installment. Can someone help me on procedures that I need to follow when I want to contact ombudsman.