Don’t make a major purchase on your credit card without checking your line of credit first, warns Consumer Action.

An online survey by the consumer group found that nearly 18 percent of people had their credit limit cut without them asking for it. If that happened to you, you could easily end up going over the limit and be slapped by a hefty fee.

But that’s not the only change the consumer group uncovered. Nearly half of the 1,083 people surveyed said the interest rate on their card had been raised.

During this credit crunch, card issuers have been reviewing customer accounts. Consumer Action says that customer service representatives at American Express, First Command, HSBC, US Bank, Washington Mutual and Wells Fargo have said that credit limits would be lowered if it appeared that a customer seemed riskier. That could be because of the customer’s credit score, late payments and balances approaching the credit limit.

Consumer Action also found that consumers were tightening their belts because of the weak economy. About four out of 10 said they reduced their use of credit. But more than a quarter were using more of their credit, and more than one-third had been charged an over the limit fee.