Breaking up with a bank can be hard to do — and expensive if you don't do it right.

Patsy Pahr of Towson says the mark left on her credit when she tried to close her Capital One credit card years ago came back recently to threaten her business license.

And Norman Chase, a retired filbert farmer in Oregon, discovered that leaving $3.21 in an unused checking account led to a debt collector pursuing him for hundreds of dollars.

Ending a relationship with a bank takes a little more work than starting one up. Both sides bear responsibility, but consumers should be extra vigilant. You might assume it's over, but the bank might not have gotten the message. And that misunderstanding can have serious repercussions, because fights with a bank can end up damaging your credit history.

To close a credit card account, call the issuer to find the latest balance and pay it, advises Ruth Susswein, a spokeswoman with Consumer Action. Follow up with a letter to the bank saying you want the account closed, noting the amount of your last payment and stating that you believe the account is paid in full, she says.

Ask that the account be reported to the credit bureaus as being closed at your request, a more favorable notation on your credit report than if the bank closes it.

The bank should send you a statement the next month indicating that your balance is zero. Sometimes, Susswein says, consumers might owe a small amount of "trailing interest" from earlier purchases, but the balance should be eliminated once you pay that.

Susswein says you should check your credit report a month or so later to make sure the account has been closed. Sometimes a bank won't close accounts, Susswein says, as a way to keep customers and allow them to change their minds and use the card again.

She also warns consumers might not want to close credit cards given today's climate, in which it might be difficult to get another card.

But if you have a checking or savings account you don't touch, she says, close it. Banks are adding new fees and you don't want to pay for something you don't use.

Pahr, the Towson woman, decided to pay off her Capital One credit card balance in late 2006. She thought the debt was wiped out when she didn't hear from Capital One.

But Pahr had some other outstanding purchases, and the bank charged her interest and penalties for not paying on time. Pahr says she paid for the purchases, but balked at paying the penalties and interest because she hadn't received a statement for months.

The bank forgave some charges, but Pahr says she had to hound Capital One to send statements. She asked that her account be closed.

By summer 2007, Pahr says, she figured everything was squared away. But she soon received another statement saying she owed $102 in interest and penalties.

Pahr refused to pay.

"If I had gotten regular statements from them, this never would have become an issue," she says.

Penalties and interest have accumulated. The last statement she received was in June, saying she owed $673.

But the real cost is higher. Her dispute with Capital One, she says, left a blot on her otherwise clean credit report.

Her auto insurer told her she could qualify for a better rate if not for the negative information. And this summer, Pahr says, the state would not renew her license as a home improvement contractor until she explained it.