Last year, Kevin Johns, a construction worker in the Bronx, did his taxes at the H&R Block store on Riverdale Avenue that he had used for the past 20 years or so. The next day, though, he got a call from the tax preparer: His return was rejected because he had already filed. Or at least, someone had filed in his name. That someone helped himself or herself to a $8,499 refund. Sharon Hawa, a disaster-relief coordinator with the Red Cross and another longtime customer at the same office, had a similar experience. Hawa said she went to have her taxes done, only to be told that someone had already e-filed her taxes and collected $6,145. Both Hawa and Johns said they were told by police detectives investigating their cases that at least 20 customers of the branch and possibly many more had been robbed by identity thieves who were very likely H&R Block employees. Both said the fraudulent filers used their previous year's adjusted gross incomes as proof of identity. 'There's only place that could have come from: H&R Block,' Johns said. On Thursday, lawyers for Johns and Hawa filed a class-action suit in the Bronx, accusing the company of failing to take steps to protect its customers' security despite previous allegations (and lawsuits filed in Arizona, Illinois and Michigan) against other H&R Block outlets. The suit came on the same day, coincidentally, that federal prosecutors announced fraud charges against 26 tax preparers from the Bronx, Manhattan and New Jersey -- none from H&R Block -- accused of collecting tens of millions of dollars in refunds through identity theft over a nine-year period. At the H&R Block storefront at 3736 Riverdale Ave., in Kingsbridge, employees said they could not talk to a reporter. H&R Block, the nation's biggest tax-preparation company, with more than 12,000 offices, said in a statement: 'H&R Block is working directly with the IRS and other authorities to resolve this situation for clients. We are standing by our clients and will do everything we can to assist them. So that we don't compromise the efforts of the IRS, we aren't able to share additional details at this time.' The police said the cases of Hawa and Johns had been referred to the Internal Revenue Service, which declined to comment, citing taxpayer confidentiality rules. In Indiana, two former H&R Block employees were charged last month with stealing the identities of more than 60 customers and pocketing at least $290,000. In the separate federal case announced on Thursday in Manhattan, Preet Bharara, the United States attorney for the Southern District of New York, said the 26 tax preparers who were charged had filed thousands of fraudulent returns using the stolen identities of dead people and residents of Puerto Rico, who do not pay federal income tax. Most of the 35,000 returns prepared by the defendants since 2001, yielding more than $95 million in refunds, were fraudulent, Bharara said. One of the preparers arrested was Kelvin Crucey, a senior vice president with the Upper Manhattan Empowerment Zone, a prominent economic-development nonprofit in Harlem. Crucey claimed $250,000 in fraudulent refunds, prosecutors said. The customers of the H&R Block branch, Hawa and Johns, finally received their allotted refunds recently after considerable headache and red tape. 