Lowered H2 - Service Air Suspension Error

[cashville]

I just got a Supercharged H2 that was lowered a little, and was permanently giving out the Service Air Suspension Error.
I went to a shop to have it raised to stock height, and what they did to lower it was weld something to the shocks to make it go down a little, I had them re-weld it to the original state, and they also put a little thing under each of the Air Suspension Sensors, they had something under it about 1" long, I had them remove it and screw it to the original place. I don't know if the car is exactly at the same measurements as the original, but it was now raised 2" total, and seems about right.
So this work was done, and the car is still giving out the same error. I tried resetting the battery, but it didn't help.

Any sugestions?

PS: Compressor is working fine, air bags are not leaking, the car suspension was never down, so it should be a sensor/programing error. Going to a GM dealer is not possible because there is none in my country.