Paying bills online can be a real convenience -- unless something goes wrong.

One of the things that can go wrong occurs when a company receives a payment but says it didn't.

Then, while you patiently explain the bill was paid because the money was deducted from your account, the company doesn't believe you and turns the "delinquent" bill over to a collection agency.

"It was a nightmare," said Linda Johnson, 61, an administrative assistant. "My problem with Verizon had been going on for 20 months. I didn't think I'd ever get it straightened out."

Verizon provided the service for the land line in her North Side home. When she went online in June 2007 to pay her monthly bills, the Verizon bill was one of the first she paid. But Verizon said it never received the payment. It said she still owed $82.52.

The yes-I-did, no-you-didn't disagreement escalated in August 2007, when she received a form letter from the North Shore Agency, a debt-collection company based in Westbury, N.Y. Verizon is one of its clients. It said she owed $82.52 and then added:

"Verizon furnishes bill payment information … to the major credit reporting agencies in accordance with the Fair Credit Reporting Act (FCRA). Unpaid balances may affect your credit rating."

In early November 2007, she was contacted by a second debt collector, Afni Inc. of Bloomington, Ill. She told a customer-service representative named "Eric" that the bill had been paid.

When she called back to ask a question, the person who answered the phone "was rude" and she got nowhere, she said.

Two weeks later, Verizon sent her a form letter saying she owed $53.22, almost $30 less than it had been seeking. It also said it considers a bill delinquent if it isn't paid within 30 days from the billing date. Then, in an ironic note, it said she could make her payment "even more quickly" by going online.

Two days later, Verizon sent a summary of her dispute with the company. It said it wouldn't be able to investigate her claim until it received from her bank a copy of the electronic transmittal sheet that shows she made the payment. The I-paid, no-you-didn't dispute continued into 2008.

Verizon sent a "final notice" form letter that threatened to terminate service immediately. It was a meaningless threat. Ms. Johnson already had switched her land line to Comcast.

In May 2008, Ms. Johnson received a form letter from yet another collection agency -- Allied Interstate of Columbus, Ohio. It said it would accept "one single payment" of $57.76 to settle the account instead of $82.52. It also said Verizon might report payment information about her account to the credit bureaus, and then added:

"With the [$600] stimulus payment coming from the government, this will be an excellent opportunity to pay this past due balance."

In June of 2008, Ms. Johnson once again heard from Afni, the Illinois debt-collection agency. It wanted $150.63. As she had done with each debt-collection agency, Ms. Johnson called, explained that the bill had been paid and that Verizon's records should show that.

When the pay-up-now calls continued into this year, Ms. Johnson contacted me.

"I'm getting bombarded with calls from three collection agencies," she said. "It's now affecting my credit. I need some help."

I called Verizon spokesman Lee Gierczynski and explained Ms. Johnson's problem. He relayed it to Richard Foy, a veteran customer-relations specialist. Mr. Foy contacted Ms. Johnson and asked her to send everything she had to show she had paid the bill. Ms. Johnson said a customer-service representative named Heather at PNC Bank sent Verizon a statement showing that the Verizon bill had been paid.

After reviewing all the paperwork, Mr. Foy confirmed that the bill had been paid in June 2007. Verizon then contacted each of the three major credit-reporting agencies and asked them to delete any references to the dispute from their respective records. Afni did the same and also apologized "for the inconvenience this situation may have caused."

"I want to thank everyone who helped me," Ms. Johnson said. "A huge problem is [gone] … and I am most grateful."