It won't be a incompatible engine so long as everything plugs in ok etc, the problem if any with compatability would be in the ecu and ignition key(chip).
Check to see if it's something silly like the fuel pump has tripped, in the kick panel, just press button down if it has, the garage doing don't sound much cop, have they checked to see whether it is a fuel or ignition problem or not, it's usually one of these missing.
tabetha