If you can avoid it, never, ever borrow money on a credit card (unless you're borrow at zero, or a very low percentage rate!).
Many credit cards charge an extortionate rate of interest, and most only require that you pay a small percentage of the outstanding balance each month (typically 2, or 2.25%). Using this calculator you can see just how long it takes to pay back money to a credit card company if you only pay the minimum.
These figures can get scary. For example, if you owe £1,558, at a monthly rate of 1.4%, and each month pay 2.25%, it'll take you over 23 years to pay it off! In that time, you'll pay £2,252.45 in interest! And that's without adding payment protection.
Increase the minimum monthly payment to 5%, and you'll pay the same amount off in under 8 years, and save yourself £1,699.56 in interest.
Remember, it's in the interest of credit card companies for you to pay off as little as possible each month, that way they gain hundreds, or thousands of pounds in interest. If you're in debt, visit The Motley Fool, and make debts with highest interest rates your first priority.