WASHINGTON - The U.S. Department of Education on Wednesday unveiled major changes to a troubled student loan forgiveness program designed for borrowers working in public service jobs — but has been criticized for its complex requirements.The new temporary changes will bring an estimated half a million borrowers closer to being debt-free.The Public Service Loan Forgiveness (PSLF) program was launched in 2007 as a reward for college students who go into public service, including many teachers, nurses, social workers and military members.