Engine Mechanical problem
2005 Opel Meriva 4 cyl Four Wheel Drive Manual 50 000 miles

I FROM MEXICO , BUT MY CAR ITS IN REPATION BECAUSE WHEN I DELIVER IT WITH THE MECHANIC FOR PREVENTIVE MANTAIN
" INYECCION CLEAN AND CHANGE OF MY BELT TIME, MY CAR WAS STILL GOOD IN THE BECOMING BUT THE MECHANIC DELIVER IT WITH THE NEXT FAIL:
IT TURN ON FOR FEW SECOND BUT IT BECOMS TO TURN OFF, IT'S NOT THE CODE OF MY KEYS, WHAT DO YOU THINK IT THIS?
THE MECHANIC CANT UNDERSTAND

THANKS FOR YOUR TIME