You can call Hyundai help line at following citing the dealership greivance.
Maruti is quick to act, don't no much about hyundai.
1800-11-4645 Toll Free
9873564645
Or email at
cr@hmil.net.
BTW what did they do, did they refilled the gas, after which the problem cropped?
It could be
1. belt tension
2. referigant oil low.
PS: I am assuming the cooling is good. i.e compressor is working, gas is R134a.