This is quite simple really, first of al check your credit card rate that you are paying right now, no doubt that you have not looked or thought about it for a good few years. Once you have done that check what you are paying in APR against some of the credit cards that are on the market right now.
When you see the difference, all you have to do is simply call your credit card issuer and ask if they would lower your APR and explain to them that you are a good customer and would like to stay a customer of the credit card company.
More times than not this will do the trick, but if they reply with a no, well what can you do? Well what you can do is have a list of potential credit cards on hand that are offering you a better deal than your current credit card.
In today’s market three are plenty of credit card companies offering 0% deals with a lower APR once the introductory period is over, than your current card. You can then tell your credit card company that you are unhappy at this and are going to switch to a credit card that is on your list, stating some of the details of the offer, this will do the trick, as the credit card companies are trying to acquire customers not lose them, to they’re rivals.