How to bypass sigma immobiliser

[Benjamindavis45]

Hello i have a v5 impreza gc8 turbo 2000 went to work no problem went to go home central locking now not working been having a problem with this for a while. now immobiliser will not disengage I didn't get the code for the key pad hen I got the car and going to put my own anti theft set up in anyone know how to bypass it so I can get it home as its stuck there and as it private property  at government building so can not get people on site to do anything please help