The banks that issue the bulk of credit cards in our country are seeing more and more problems with delinquency. Their response has been to raise interest rates across the board -- even on people who have not been late on their payments in any way. Sometimes they try to justify the hike by telling you that you've cross defaulted, which means you're penalized for being late on another bank's card. But your bank can also arbitrarily raise your interest rate -- sometimes up to 30 or 33 percent -- on just 15 days notice. So what power do you have? Much of the time, you have the option to suspend charge privileges on a card in return for being able to pay off your balance at the old rate. But if you have other credit lines, vote with your feet by threatening to take your business elsewhere. Try pitting your lenders against each other to get the lowest interest rate.