"Who/where you lay the blame off to someone other than yourself is your business?"
You have a interesting "saga" that just didn't ring right with me at all.
I would recheck your part # - run your VIN# thru EPC yourself to confirm the correct MB part # A 149 470 03 05 (best to use Explorer rather than Chrome or Firefox for EPC use) - and from your report I suspect you have been given/getting the wrong part# all thru this deal. Not right at all actually.
You have been given/getting a "newer" style gas cap not intended for your 2000 E320 - as a result, the metal fingers on the newer gas cap are getting bent when the wrong cap is getting tightened down on your car.
Who/where you lay the blame off onto someone other than yourself is your business - rage against MB corporate if you want - whether you choose to blame your indie, or blame who might be supplying the gas cap to your indie (most indies get gas caps from non-dealer sources for a bit less than MB dealer "wholesale" prices)... who you rant against really isn't my concern.
Now... on newer MB's it is much easier for a owner on a newer MB to mistakenly twist the new stlye cap on lopsided, and that bends the ears on the new style cap, and yes that is a "problem" that newer model owners have that earlier model years did not have - but since that genuine problem on newer MB'x doesn't affect you I bet you won't pay attention...
What? I paid for a part that was ordered based on full disclosure and documented information.
I guess it is my fault for expecting a competent person to provide the necessary goods based on facts. I knew I would be the culprit in the end.
The customer is never right.
The Indie I use has forgotten more than any of the new techies at the dealership. I'll leave it at that.
As for parts the local MB shop has been known to screw up. The Indie has already reamed them so no need for me to do the same. Blame is something I could care less about and FWIW, they have the VIN on record at the INDIE and the DEALER. So that's moot.
BTW; I love INDIES. They are the ones who keep the old ones running. I can guarantee you that once they get a certain age the dealership doesn't want to see them anymore.
Show them an MFI car and they'll run like a scalded rat.
I'm going to keep the old cap.