TLDR:- Got the tire replaced by Pirelli for zero cost . Thanks to them.
So very recently i discovered that there was a nail in one of my rear tires. I had not purchased any additional tire warranty from the dealer/mercedes . Brand new car .. ran hardly 2000 miles . Called the dealer and they said run flats can't be repaired , rather they have to be replaced . The nail was in the shoulder of the tire too (so i knew they had to be replaced) . Car dealer said nothing can be done and I would have to pay for it .
Looked up on Pirelli's website and found that they have a road hazard warranty for one year on their tires . Called Pirelli, they asked me to go to the car dealer and give them a call. The mercedes dealer simply refused saying that they dont deal with Pirelli. They did suggest me to go to discount tires.
Went to discount tires and they were just great . They called Pirelli and the customer service approved the tire exchange and after a week , the tire was replaced for no cost .