As a Mercedes Mechanic for over 30 years, Yes, without a shadow of a doubt, they would not give you a new car. They would fix it [As a McLaren and Maybach tech too, they would not either]. Matter of fact, I know when there is damage to cars when they get shipped oversea to America, they are repaired, and sold as new. As soon as you purchase it, you will not get a new one. If you Lemon Law it, you rarely ever get a new car. That said, there are bigger money issues and not to mention, there is a VIN that you would have to wonder about.
Not saying you are right or wrong, just saying. Especially since they are warranting a frame, they never said you are entitled to a new one [guessing on the fine print of the warranty paperwork]. It is usually in their best interest to set you up with a new one. That's where a good employee would step up and perform a final QC inspection before they ship it to you. If that was repaired before you got it, you most likely may have not noticed it and we all would be having a good Thanksgiving day [at least in the USA].
Yes, you're right. I've heard similar issues related with bmw also..
And the main reason of all my cases are due to the poor qc of their factory, as i've mentioned many times.
Hope you have a good Thanksgiving Day and holiday:)