Many convenience stores are capping how much drivers can spend when they swipe cards at automated gas pumps.

That's because the credit card companies have imposed limits on how much they'll reimburse stores for disputed purchases at gas pumps.

For Visa and MasterCard the limit is $75.

With gas costing $4 or more in many parts of the country, that's not enough to fill many pickups, sport-utility vehicles and vans whose tanks often hold 20 gallons or more.

The best way around this is to pay inside. There's no limit on how much you can spend if an attendant swipes your card at the counter.

And if you're struggling to keep up with your monthly payments, take a look at our advice on how to pay off credit card debt.