When was the last time you took a look at your credit card APR (Annual Percentage Rate)? You may think you know what the bank is charging you for the use of their money, but you might be surprised to find that terms have changed, and you're now paying as much as 18 to 20%. The U.S. average is around 18%, and I believe that is much more than you have to pay—especially when you've been a good customer with that bank.

So what do you do if you discover that you are paying too much for your loans? Well, quite simply, make the bank lower your rate. Sound impossible? More than half of the time, I've been able to make my banks lower their interest rates. The trick is to have the right deal-breaker.

A deal-breaker or BATNA (best alternative to a negotiated agreement), as William Ury, author of "Getting Past No," would say, is what you will do if you don't get your way. It's the threat of leaving the car dealership if they don't agree to your price, or the I'll-call-my-lawyer option if you can't settle a dispute.

Some of you might be thinking, "What kind of threat can I deliver to my credit-card bank to make them lower my rate? What deal-breaker do I have?" Realize that there are options, and start taking advantage of them. The first place to look is in your mailbox.

You know those low-rate transfer credit-card offers that go from your mailbox straight to the "circular file"? Banks attempting to get you to switch sent out more than 3 billion transfer offers last year. So, I know you've seen them. Take a closer look at the next one that arrives—probably today. The best part about that offer is that you need not apply for the new credit line in order to make good use of it.

What that offer becomes to you is the deal-breaker—the leverage you might need to persuade your current bank to lower its APR on your account. How?

Take out your credit card, flip it over, and call the customer-service number on the back. After you're done going through the torture of entering your credit card-number and information in the automated voice menu, choose the option that gets you to a human. Remember to be calm, yet firm. Your conversation could go something like this:

Account rep: "How can I help you today?"

You: "I've been looking closely at my credit-card statement, and I've noticed that your bank has been charging me 18% interest for a while now. I don't believe I should be paying that much interest."

Account rep: "What would you like me to do?"

You: "Lower my APR to something more reasonable, like 6.9%."

That might be all it takes to make them lower your rate, but I want to prepare you for a bigger battle.

Account rep: "I can't do that?"

You: "Who can?"

Account rep: "Nobody really, we can't just change rates like that."

You: "Can I speak to your supervisor, please?"

Account rep: "Sure, please hold."

Supervisor: "Can I help you?"

You: "Your bank is charging me way too much interest, and I want it lowered to something like 6.9%. This is the deal: I'm holding a credit offer in my hand from [name the bank]. And they're willing to give me 4.9% for 6 months, no annual fee [read the offer terms]. I bet your bank has better offers for new, unproven customers than they do for established profitable ones, don't they? I see no reason to stay with [name] if they're not willing to treat me better. I have plenty of other banks to choose from."

Supervisor: "You know that if you take that offer, the rate will go up in six months."

You: "Well, I'll worry about that six months from now. And that's six months without any high-interest charges from your bank. Or six months that your bank doesn't make any money from my account."

Supervisor: "What can I do for you?"

You: "Look, I'm not asking for you to lower my rate to 4.9%, but I do need a reason to keep my balance with your bank. How about 6.9% or 7.9%?"

Now, at this point your chances are 50/50 as to whether they are going to lower your rate. Your bank may come back with an offer like 7.9% for six months or a low-annual-fee card at a lower rate. In general, you should always take the lower rate, even if there's a time limit. You can always call back in six months and do this again.

Remember that you need a real credit offer to do this. Without a deal-breaker, you're just begging; and you won't win by begging. Success here may also depend on how good you've been at handling your account—paying on time. But no matter what your credit history is, you should make that call, because you may be surprised to find that the bank really wants to keep you as a customer.

It cost banks plenty of money to find a new customer. The competition for a piece of your credit business is intense. Banks are fighting to get you to switch, so it is truly in their best interest to keep you, a proven and profitable customer.

How much can you save? Here's some incentive to make that call today. Let's say your current rate is 18%. If you can get your bank to drop its rate to something even as high as 9.9%, you'll save a bundle! The dollar amount saved depends on two other factors: (1) how much you owe and (2) how much you're paying per month.

For example, if you owe $5,000 and you're making payments of $100, at 18% it's going to take 93 months to pay off the card; and it's going to cost $9,300. However, at the new rate of 9.9%, it takes only 65 months to pay off the card, for a total cost of $6,500. You save the difference between $9,300 and $6,500, which is $2,800!

That's $2,800 for making a phone call—do it now!