Drastic jumps in interest rates have occurred even when a cardholder has had a record of paying on time, like in the case of Carita Marie Gamble.
The 72-year-old grandmother, who lives on a fixed income, was shocked to see her rate jump from about 16 percent to more than 26 percent last month.
"This has put me over the top financially," said Gamble, who has emphysema and had a tracheotomy.
Her monthly income of $1,100 has taken a huge hit now that her credit card bill has increased more than $400.
"I worry that she's not going to make it or she's going to have to sell her home. And we've looked into that," said Gamble's daughter Carita Marie Gamble.
The elder Gamble said she has always paid her Chase bank bill on time, even if it was just the minimum amount. The Gambles were shocked to learn the interest had increased because the mother had opened a new credit card. The bank told Gamble the new rate was permanent.
While Chase bank would not speak to ABC News on camera, Gamble's interest rate did decrease after "Good Morning America" contacted the bank. The rate is lower than it was before the hike and Gamble said she was told the interest she paid would be refunded.
"I'm not asking to make my bill go away. I did not like the way I was treated. And I feel they're money grubbers. That is not the way business is to be conducted," Gamble said.
Congress Steps In
Radical rate hikes like Gamble's are perfectly legal. In fact, since 2003 banks' penalty fees have jumped from more than $11 billion to $18.1 billion last year - a 65 percent increase.
But Sen. Carl Levin, D-Mich., is trying to change that by leading a charge in the Senate to conduct hearings and introduce legislation to stop banks from raising interest rates on customers who have paid their credit card bills on time.
Lawmakers in the House of Representative have proposed legislation, too.
"Many cardholders can be paying their cards on time, playing by the rules and they find their interest rates have gone up. This is totally unfair," said Rep. Carolyn Maloney, D-N.Y.
An industry representative said the variable rates of credit cards often lag behind after a change in the Federal Reserve's rate, but many consumers are seeing a decrease.
"In general interest rates for credit cards are going down," said Nessa Feddis, of the Credit Card Practices Attorney for the American Banker's Association.
Both competition and pressure have fueled changes in the industry, she added.
Feddis said people who are deemed riskier borrowers should expect their interest rates to be higher, but card companies allow them some leeway.
"They have a vested interest in having loans that can be repaid," Feddis said. "If you pay on time for the next six months, your rate will go down again," Feddis said of customers who have missed a payment or paid late.
While critics have complained that credit card disclosure statements are difficult to read and interpret, Feddis said consumers should pay attention to them.
"The disclosures could be better," she said. "The disclosures should be read and people can understand them."
Mailboxes across the country are filled with 0 percent introductory rates, which often make a rapid jump after six months. It's all in the fine print.
"It's hard to find that 0 percent is a bad deal, even if it's for six months," Feddis said.