A group of small business owners in Maine’s mid-coastal area say they want the health care insurance overhaul bill that was passed by the Legislature last year to be repealed. Members of the Maine Small Business Coalition plan a news conference Thursday in Boothbay. They say the Republican-backed overhaul law has caused rates to spike by more than 25 percent for many businesses in the area. More than 1,200 members of the Maine Small Business Coalition have signed petitions, written letters and lobbied in Augusta against the law. Since its passage, they say 90 percent of small businesses have seen their rates rise. Representatives of four mid-coastal businesses are to speak Thursday. Supporters of the law said when it passed it would drive down rates and help small businesses.