If you take it back more than 3 times for the same problem and jump up and down and up and down again, it wouldn't be unheard of for them to give you a new vehicle. I have seen this a few times.
Also, you need to go to the top on this one. Don't trust who you're dealing with IF they are giving you this load of sh--.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS