CARE CREDIT - GE CAPITAL CON CC ripoff dishonest misleading Dayton OHIO

I used the credit card to make three different purchases. Two purchases were less than three hundred dollars, and one was for $726.95. I was informed by the merchant that if the purchase was less than three hundred dollars that it wouldn't qualify for the 90 day same as cash promotion. To make a long story short I paid both of the purchases that were less than $300 dollars before their due dates, and still was charged with a finance charge.

The customer representative, and supervisor said three different reasons why this occurred.
1- They said that it was the merchants responsibility to let us know that if the amount was less than $300 dollars that we had 25 days to pay the amount without getting a finance charge, even if the due date was different.

2-Than he changed it by saying that this was stated in the GE CAPITAL CONSUMER CARD CO. CREDIT CARD AGREEMENT.

3- After letting the customer representative know that the CREDIT CARD AGREEMENT didn't state anything about having 25 days to pay, but it did indicate "A Finance charge is assessed at the end of the billing cycle if not paid in full by the payment Due Date". Then the reason was changed to, that the merchant should of had told me that if the purchase was less than $300 dollars that automatically I would be charged with a finance charge.

-I would like to know why do they put a due date on a statement if the credit card company is still going to charge you a finance charge, even though the regular purchases (not in a promotion) are paid in full before their due date? Where are the laws protecting consumers from being ripped off??

Edwin
Weston, Florida
U.S.A.