Inconvenienced by MiWay.

I called MiWay during the week to change my debit order date. The debit order used to on the 25 every month, I changed the date to last day of the month. I was advised that there was a pro rata amount of R205(forgot the exact amount) from the 25 of Jan to the 31. I accepted the mandate of the new date which is the last day of the month(31st Jan). But to my surprise the debit order went through on the 25 Jan including the extra amount of R205. Can I please get my refund because I was changed an extra amount for nothing. The date is still the same.