mk5 gti MK60EC1 abs issue after module swop

Lol brake light switch is working perfectly!!! I've already swopped it with my own cars switch but to no avail. ..i to feel the pressure switch could be where the issue is..but thats a matter of getting a very expensive hydraulic pump unit to test.HUGE GAMBLE!!!! If i get a complete abs pump with control module second hand. .could it be programmed to this car??? How would i know what part numbers would be compatible with my car?

Guys just an update on this situation. Customer couldnt wait for me to source a second hand unit and decided to take the car back to the dealership...abs module and pump were replaced and the vehicle is now sorted.....