The (mobile phone) situation in the US is different to that in Europe, but
something happened to me in my 2001 car with a factory-fitted phone kit that
was similar in effect to what you are describing. The cradle was suitable
for a variety of Nokia handsets, this being fine as Nokia has the biggest
market share. However, about a year later Nokia's principal new phone
(6310i) did not fit anymore, despite having a '6' prefix.
Equipment modification would have cost GBP 250 (Germany) or GBP 400 (UK). I
Even though it wasn't entirely MB's fault, fortunately my (German) dealer
found a way to do the upgrade FOC as a warranty issue... :-)
I had to arrange a drive to Germany from London, as I had bought the car
there. It took a few months to find the opportunity but it was no hardship.
Have you contacted MB US? Try the marketing director.
For direct contact replace nospam with schmetterling