I have one fitted by that guy, drives a black astra iirc? first problems arose when he didn't screw down the earth properly so it the current moved onto the next control box and set all the wipers off and stuff when i went to open the car!
Had some immoboliser problems with it too, not disengaging properly causing startup issues. Doubt I would get one of them again tbh clifford next time i think.
and back to your topic, signal isn't great on mind either. I could get it 20ft if lucky but sometimes i have to be as close as next to it like you said.