Capitec bank access loan

I need help with Capitec bank access facility loan. I've recently changed pay days from the 30th to the 15th and thus asked them to change my debit orders to the 15th. My monthly debit orders increased enormously by 800.00 which when I calculate over the period of 18 months will be 12000. 00 and more.

I tried calling them several times and I still didn't get the answers, instead one of the agents said my installments are increasing because I will be skipping a month whereas I have already paid my debt 15 days earlier this month. I am really disappointed because I was not on arrears, also I have other things to pay for besides the loan. How am I going to cope with soo much money sucked out of my account?