skipped control chain

Drive since Feb.2009 an i30 1,4liter 109 Ps with gas system.This morning the engine did not run anymore !! In the workshop came the diaknosis control chain skipped ! The car has this month warranty but the workshop meant with the installation of the gas system the claim expires !!! Can someone help me? Am really angry , if I should pay the repair itself !!! 🙁 !! Ps. What should the gas system have to do with the control chain ?