If your credit card issuer raises the interest rate for anything other missing a repayment, you're usually better off cancelling your existing card and hitting the price comparison sites to find a new one with a lower APR.
What rules do your credit card company have to live by?
Not to increase the interest rate if you have a debt problem. For example, if you are two or more payments in arrears or a repayment plan has been agreed.
To tell you about any increase (they have to notify you individually unless the interest rate is linked to the bank base rate or another rate, or unless the increase is just because a promotional period is coming to an end).
Allow you to close the account, and clear the debt at the old rate of interest if you notify them within 60 days of the increase.
Credit card companies have also agreed not to increase your interest rate within the first 12 months (as long as you don’t breach the account’s terms and conditions) and not to increase it more often than once every six months after that.
Switching to a new credit card
If you do choose to close the account, you could consider switching to a different credit card. For example, one that offers an interest-free period on balance transfers.
Head to a comparison site, they’re the best way of comparing like-for-like. Most sites have effective calculators to show you the best card you might be approved for.
If you want to make a complaint
If you feel that your credit card provider hasn't played by the rules, and that you've been treated unfairly then you should complain to them first and foremost.
If you're not satisfied with the response, then you can complain to the Financial Ombudsman Service.