Engine check light

[BirlaBose]

Hi guys, recently experiencing a nerve wrecking issue with the engine check light on my W212. Long story short... 

1. ECL appeared 3 weeks ago, and i went to the reccomended workshop to rectify the issue. Was told its a sensor trip, and the fault code (P2015, P201600) was erased. (Drive home super duper happy).

2. Next morning, light appeared. (Sianz). Went over to the workshop aft a day, was told that the thunder flap wasnt functioning properly. Wasnt convinced as my car didnt show any signs of failure. Said thanks and left. 

3. Went to another workshop, upon multiple inspections, they discovered ECU connector pins had few markings made on them. Was reccomended to talk to sales man who sold me the car, as fault appeared within 4 months of purchase. 

4. Salesman got me to go over to his another reccomended workshop. Workshop confirmed that ECU has problems. 

I seek my fellow Merc Bros advice on what i could do next.