Don't know why the dealer would fault the booster without a proper diagnosis (or have they diagnosed it). But yes to answer John's question, there is a part in the booster for the BAS system which isn't available seperately, so it could need a brake booster because of this. I believe it's called the diaphragm travel sensor, could be wrong, maybe MB Stars will know for sure. There is one sensor which IS available seperately and one that isn't. (PS: Of course the one that IS available seperately I've never seen fail
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Sight unseen I'd more lean on the brake switch too, common on the 163, MORE common on the 210 it seems like. If it does this again if at all possible make SURE the brake lights are working. There are 2 sets of contacts and depending on which set fail you may not have operating brake lights, If EITHER set fail you'll get these warnings on the dash though. So you can get the warnings and may or may not have operating brake lights, so use caution.
Gilly