Probably referring to the ECM (engine control module). Might be called ECU in the manual.
Just buy one used - mine went out a few years ago and I bought one for $50.00 from
www.car-part.com.
I think there are several different part numbers that will work in your car.
Forget the dealer, no reason in the world to buy this part new. Did they even swap yours out with a known-to-be-good unit to verify that they have actually identified the defective part, or are they shotgunning parts at the car?
Takes 5 minuted to put a new one in, max. Just unhook the battery, then swap out the unit. It is located near the battery by the firewall on 124 cars, I think.
What is wrong with the car?