In an era of increasing scrutiny over consumers’ ability to buy big-ticket items (mortgages, cars), the last thing a guy needs is for a cell phone company to wrongly ding his credit score.

That happened to Jim Henning in Knotts Island, Va., after Verizon Wireless bought Alltel. Alltel subscribers had to switch to Verizon, so Henning, like everyone else, recently did so. And then Verizon billed him $400 for canceling his contract.

“I called them immediately and the lady said don’t worry about it, it’s been happening with the changeover, just disregard that bill, which I did,” Henning told Hampton Roads TV station WTKR.

Problem was, Verizon kept sending Henning letters ordering him to pay up. Finally, a customer service tech instructed Henning to send a cancellation fee to Alltel and then Verizon would credit him the $400.

So Henning did just that, in two $200 installments. (Smart guy, he kept the canceled checks as proof.) And he received the credit from Verizon. But – and you knew there was a “but” coming – something went wrong. Verizon still didn’t credit Henning’s account and then turned over his supposed late payment to a collection agency. Henning said he could have lost his job – the nature of which wasn’t disclosed – over the matter, but didn’t, thanks to “a very understanding boss.”

He also fears the collections status will hurt his credit score. He’s saving to buy a house and he’s afraid Verizon’s collections action may have put that goal in peril, a valid concern since banks no longer are handing out mortgages like candy.

In the meantime, it took a phone call from WTRK to Verizon and the collection agency to get the matter cleared up. Verizon says it’s updated Henning’s account and the collections agency says Henning’s bill is considered paid in full. Verizon also told WTRK it’s informed the credit agencies of the mistake and taken steps to keep Henning’s credit from being affected.

Verizon closed its $28.1 billion purchase of Alltel just less than a year ago. The acquisition catapulted Verizon to the No. 1 wireless service provider slot in the United States, giving it more than 80 million subscribers.