Unclear information given, resulting in charges

I was recommended to move to a Fusion account to reduce by banking fees. I was told there would be a credit facility which had a thirty day interest free facility, upon making use of this facility via EFT for less than Thirty days, i was charged over five hundred rands interested. I then queried this and was told it is only interested free if i had used to swipe my card, as stated in the agreement, but no where does it does you get charged if you use the online system since day one. This is unacceptable. Be clear and stop looking for ways to charge us.