Mongoose M60 or M80 R33 GTST SII

[trel]

Hi guys as topic states I have POS Mongoose m60 or m80 I'm not 100% which model. I bought the car with it installed.

Having a look under the dash and in engine bay, whoever installed it did a shocking job, wiring looks butchered. 

I've had issues with it from day one, going off as I drive hitting bumps, car stalling due to the immobilizer etc. 

So tonight went outside only to hear a loud buzz coming from the siren itself no matter what I do I can't turn it off. (Don't have the skeleton key). My brake lights were on as well and when you try to turn ignition to on there is no power at all. I've disconnected the battery and stuffed the siren with rags until the backup battery goes flat and it shuts up. I'm not confident with electrical let alone an immobilizer to try and have a crack at it myself. I'm at a loss I need an auto elec in Melbourne who is a pro on Skylines. 

Can anyone give me a trusted contact please? 

Apologies for the long post but thought I'd share what is happening. Possibly this has happened to a member here also who can point in the right direction.