NHTSA Complaint #11473597 — 2012 MERCEDES-BENZ C300

So here I am - another "happy" driver with a rotten subframe. Started noticing instability on the highway speeds a few months ago. Cracking noises lately. Since I use this car my very honest mechanic immediately told me that my rear subframe is completely done and I should not be driving the car until it is replaced. He quoted me $4500 (OEM parts + labor), but suggested that I take my car to MB and insist on covering the repair costs as this issue did not seem typical to him at all. I started googling and ended up here. Seems like this is a common issue and sounds like MB will replace the subframe for free in some other countries (cananda and Germany, .The dealer said the repair will cost Over $5000.00 This is a safety issue, A real big one. And the fact it's covered in other countries is so not fair. I own another mercedes and now I feel the cars are not as safe as they used to be. Please let me know what I need to do next