Dozens of San Francisco restaurants are under investigation for exploiting a new city program by keeping customer surcharges instead of spending them on employee health care, city attorney Dennis Herrera announced Friday. Offending restaurants have until April 10 to spend at least half the fees collected on employee health care or face consumer fraud lawsuits. Unspent fees must then be turned over to the city, which will use the money for future enforcement of the city’s landmark universal health care program. The so-called Health San Francisco program launched in 2008 and requires city businesses to set aside $1 to $3 an hour per worker for health care costs. Many San Francisco restaurants have taken to paying for the program by charging diners an extra fee for every meal according to a recent report at the Fresno Bee.