Re: 156 Key problem
firstly, buy a secondhand key (£10), replace the immob chip and remote PCB with your originals, and then replace the metal part with a new one cut to your original key (timpsons £6 for uncoded copy, then cut it to correct shape to fit your key, i use a dremel for this). now you have a working key.
i should point out, to reomve the orignal metal part you need to drill the round part inside the key, you'll know what i mean when you have a look, use a 6mm drill bit and take it easy, you dont want to drill through, just enough to free the metal part so you can slide it out.
the immob problem you are having sounds like the very common connection problem between the ignition switch aerial and the codebox. wiggle the wires at the bottom left of the fusebox and it should be sorted. failign that disconnet and then reconnect the aerial on the igniiton sewithc and the blakc box up behind the fusebox (follow wires from aerial to find it).