Bosch power drill malfunction
First, make sure the "hammering" you are experiencing is not the clutch, doing what it is designed to do. 

It is not uncommon for the switching mechanism from drill to hammer-drill to break and stop functioning properly. Whether it is worth repairing depends, Bosch sells different grades of tools. A professional grade Bosch hammer drill might be worth repairing, a consumer grade one would not. To even get a quote on repair cost you have to pay to ship it to an authorized repair center (or find one and take it there). 

Consumer grade Bosch hammer-drills sell for as cheap as $60 (U.S.) at discount hardware stores, your repair price would likely be equal to or higher than that.