Hopeless helpless mercedes!

Utterly disappointed and bemused by the fact that my brand new mercedes that i have less than 3 years and little less than 60000km (still under warranty)on the clock can not be fixed for the SAME ISSUE by a “mercedes benz dealer” in the pass 2 months my car has been +- 4 times for the same reason back to mercedes......misfiring/engine light coming on. Everytime we get the same response after taking it back to them “ we sorry we will sort it out” upon picking the car up and been told everything is sorted now...after a day (if im lucky) the same problem accrues...+- 4 times already...i am now tired of going back and fort with my car to the dealer as clearly they have no clue as to how to fix the problem...i do not want the car anymore and would like to get my money money so that i can rather purchase a relaible car other than a mercedes !!