I would first take the car to any alignment place and have them do a
printout of before and after result and give it to you. You will have to pay
for this service but if your rear tire is way out of alignment, the shoip
will inform you and give you a proof.
With this proof and along with all the receipts of you asking them to fix
that rear axle... you have a concrete reason to contact MBUSA for corrective
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If what you said is correct and the car is new, I'd suspect damage before
they sold you the car... possibly an accident, either car and curb, or car
axle bent during transportation... etc.