Customers comes last here and his satisfaction is least in priority list once they sell the car and pocket the cash.
Its horrendous to read what you have gone thru and im sure its very killing for you to go thru after buying brand new car from such a respectable brand like Hyundai. If anything have to be done they must have done it by now and i dont think its worth chasing these morons anymore. If i am in your place immediately after 3 months i would have escalate this problem to Dubai Police, some consumer rights.ae stuff and to Hyundai Korea and publish this experience in 100 facebook and internet forum like a flash flood. Trust me within days and weeks Juma al majid will come and replace your car, as only thing they care about in this region is bad publicity and one of my colleague tried same with Nissan (but on very small scale) and received very nice feedback and result.
Wish you good luck and really my heart cries for your suffering, i pray you get this problem sorted and able to enjoy your ride on which you spend hard earn money.