I'm hearing you loud and clear, and I'm sure they do want it out of their shop, because they are just tossing stuff at it.... like the abs unit...
now, the speedo worked when you brought it in..... they supposedly tossed parts on the bike, which had the Rostra installed...
what exact harness did they supposidly replace??? and when they installed these harnesses, what re wire work did they do to re install the signal to the Rostra?
then, their re wire work caused the failure of the speedo sensor???
I just went over the circuits, and testing procedures for gage functions, and also the speedo sensor, and feeling like they jacked up a connection or two...
either at the gage cluster plug pins 11 & 12, or down near the connection to the speedo sensor.... that sensor is a prox switch, which senses induction as metal passes a surface, no physical moving parts, and you coud connect 12v to any pair of wires on that sensor without damaging it...
I think during their testing, they made errors in the procedure, and caused the damage to the sensor.
as I said, the gray wire from the rostra only senses a pulse, and applies no current to the switch.
if they remove your rostra, and cobble up the harness installed, and don't do it in a manner to prevent shorts now after they remove all your wires... you're pretty much screwed, and chasing this down after will be a nightmare, especially when the scoot you out the door.
I wish you the best of luck,