Tom- sorry to read about your ASR fiasco
...was wondering if you are the original purchaser/ owner of your e500 and how many miles on your car currently?
...maybe some type of shared expense/ good-will MB warranty may be negotiated (with MB higher powers involved) in the event you are original owner with ~30k miles on the car?
...another avenue may be to research an independent with e500 expertise and forge a good relationship with this shop (you may be able to find one using search here)
also, benzmac, donnie, italianbenz, & other techs here may also be able to shed more light from their experiences..