You shop the "sales," even for credit cards. You can't beat a bargain. But when you're paying with credit, if you're not careful, you may get more than you bargained for; rate hikes and fees that wipe out your great deal. That's because some card issuers are resorting to these card tricks:

• Changing the due date on your card payment without your prior knowledge. Some companies change the due date almost every month. If it's due one month on the 20th and due the next month on the 15th, you'll have less time to pay off your balance and are more likely to incur a late fee. Late fees on bank credit cards are soaring, with the most exorbitant topping out at $35.



• Shortening grace periods while simultaneously raising late fees. These two actions mean less time to pay off your balance. And federal law requires notification of changes only 15 days before they take effect�leaving you no time to make alternate arrangements.



• Putting you in the middle of two sets of pricing criteria when card issuers merge. The new issuer may have more stringent requirements than your old one. However, most companies do take some time to assess their new customer base before making changes.



• Charging higher interest rates because the card issuer moves to another state that has no cap on its interest rates.

To avoid surprises, read all mail from your card issuer. Note whether rates and grace periods have changed, and if they have, find out why. Also, keep track of your payment—when you send it and when it is due.

If you're not satisfied with your credit card's rates and terms, see your credit union. For starters, credit union cards charge an average annual percentage rate three and a half percentage points lower than bank credit cards. Also, for credit unions that charge annual fees, the average fee is more than $3.50 less than the annual fee on the average bank credit card.