I'm not sure why they couldn't make the rear window work. If the car has any sort of AUX features then it will work, trust me. Each aux channel has a set of features you can program it to do..
Default for each aux channel is validality, which is basically when you push the button on the remote it sends the output for as long as you are holding the button.
The next is latched, which continues to send a signal until you push the same button again.
The next is latched and reset by igntion, which is exactly the same as before but it also ends the transmission when the ignition is turned on.
Last feature is 30-second timed...which basically once you hit the button it will transmit a signal for 30 seconds. This can be changed to any time with a bit-writer.
The only way your guy couldn't have got this right is if...
1. He tried using the output from the alarm to actually drive to motor.
The outputs on the alarm are generally 200 mA... that is not even close enough to try and drive a motor.
2. He didn't reverse the polarity on the output. Since you HAVE to use a relay in order to make this work, this is very unlikely. The outputs from the alarm are -, and you'll need 12V to power the motor.
3. He just doesn't know what he's doing.
You'll need a bitwriter anyway you look at it unless you window conviently takes 30 seconds to roll down. But trust me, this can be done.