A former Home Depot subcontractor is suing the Atlanta-based home improvement giant, claiming his contract was terminated after he pointed out accounting irregularities, the Associated Press reported.

Raymond Hammond filed suit May 26 in Mecklenburg County Superior Court in North Carolina claiming that in November 1999 he told Home Depot co-founders Bernie Marcus and Arthur Blank in a memo that the company had overpaid him for every installation he did for Home Depot stores in upstate New York, the AP reported.

He says he received e-mails from about 70 other Home Depot window and kitchen installers around the country showing they had also been overpaid for installations, most averaging about $20 per job, but some by as much as 20 percent above the actual cost, according to records related to the suit.

Hammond’s suit says his contract was terminated in August of 2001, shortly after he reported the overpayments for the second time, this time to Home Depot’s general counsel.

In a statement issued on Thursday, Home Depot, the nation’s largest home improvement chain, called the lawsuit "patently frivolous," and said it had done nothing improper, the AP reported.

The company chalks the errors up to "key stroke errors," which were fixed after an investigation into Hammond’s claims. The company also said the billing confused Hammond, the AP reported.