Changing debit order date

<p>My husband called MFC on 30 August to change his debit order date from 1 st of every month to 26 the. He spoke to Zunya T. Then after his monthly instalment increased only because he changed his debit order date. This is robbing. I have changed my debit order date from 1 st to 25 my installment never went up. Why does MFC increase installment. I have sent email to quiery this no one response received. </p>