hahahahaha
ur experiencing same thing i experienced two years ago, heres a tip do not f**k with the ECU lol
my car came without a ECU and ENGINE
it depends on your car
93-96 w/o laser key means ecu is only coded to ur engine not ur car
96/7-onwards with laser key means ur f****d, have to make sure u get the exact one for the car,
lucky lucky mine was a 94 normal keys without chips in the keys so i could find one so long as it was out of a c220 it was ok e.g. elegance, sport didnt make a difference
remember ecu and engine must be compatible sometimes some of the loom that goes from the ecu into the engine some of the thermostat sensors and that into the engine have to be changed but u can go to dealers and do that not a problem,
to program u can spend but there is no need to if anything there will only be one odd thing wrong like on mine, everything works perfectly accept my wiper can work even when the car is switched off, which can be programmed but i know to switch the wiper off so what the hell
so u know dont get put off with what dealer says make sure u just get it to start and drive and do all the normal things if that works everything is ok i mean it can be programmed further
cya
hope it helped
heman