If you have a spline type stem then renting (or purchasing) a faucet handle puller is the way to go. Generally (in the U.S. a good one shouldnt cost over $10.) that will take off the handle. If you cant afford that then gentle tapping the handle with a piece of wood in all places, back and forth and so on, will eventually get the handle off. What generally happens is that two metals sit next to each other for so long that the electrolysis creates a bond between them making them very hard to get apart.