engine issues help! :(

[checkmate123]

Hi, i have a 54 plate passat highline which in the past has had its engine changed, i assumed it was changed to the avb engine til i realized someone had scored off the sticker on the timing belt cover. then today i went to put in my 4pin coolant sensor only to find its a 2pin which is sitting in a different place to where it is supposed to be. i now have no idea what engine i have what do i do