Poor Service

I brought in ou car Hyundai I20 for a 45k service and reported a fault on the fuel gauge and 2 weeks later the fuel gauge problem was fixed, after that when collecting the car i noticed that it struggle to start but i said maybe i did not start it correctly but i was wrong the next morning the car was worse, it starts in the 3rd attempt, i reported it that my car had no problem with the starter but after collecting its now giving me problems, they attended to it trying what ever, changed the fuel filter claiming because it was dirty thats why it strugles to start but still not fixed up to now, i reported the matter with Head office but the said i must deal with the principal manager i did speak to his assistant because he was on leave and he promised to come back to me but he never did, i had to call again, and today when i call him, he refers to me to the Workshop manager, she as well said she will call me, i have been waiting and waiting but no one cares to call, this is the worst service ever, My car was okay when i brought it in