by Jay Gray
If you're like most, you're in the middle of a holiday shopping frenzy.
But before you swipe your credit card one more time this season you may want to take a closer look at your bill.
Your interest rate could be changing without you even knowing it.
Millions use plastic to make ends meet this time of year not knowing there could be a shocking surprise as they work to pay-off that debt.
Michigan Senator Carl Levin said, "Folks who pay on time, pay at least the minimum amount due and wake up and find out their interest rate has gone through the roof."
Even though there are no late, or missed payments cardholders can still see interest rates jump by 15-percent or more.
It can happen with little warning and seemingly for no reason.
Credit card customer Millard Glasshof saw her rate go up.
"I was getting frustrated. The more I paid, the further behind I was getting," she said.
As part of an on-going congressional investigation into the credit card industry, lawmakers Tuesday heard from several customers caught in what they consider an unfair interest rate trap.
"Of the $5,616 made in payments to Discover. $3478.39 went to interest. It's hard for me to get my mind around that," said credit card customer Janet Hard.
Corporate leaders from the credit card industry point out that the rates often change when a customer's credit rating drops even if their account is in good standing.
Roger Hochschild, President & CEO of Discover Financial said, "I think we are continually evaluating are practices both in terms of educating customers as well as in the disclosures we provide."
Still Congress and consumer groups warn credit card customers to keep an eye on their interest rates and any fine print on their bills.