call back and talk to someone else
or go to Cliffwood

Bosch is Bosch, they shouldn't have a problem with working on older MB parts as it's patently easier than newer stuff
unless they just don't know what they're doing

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)