ok, well I've worked it out, and to tell the truth am pretty p'd off!
the power for the controller and defi link has been spliced into the old iso connector for the old radio! rather than into the cars actual wiring or loom!
so ive put the new stereo in with new iso connector, which removes the power to the old iso!
i guess my options are to try and buy a new radio to fit the old iso connector, it was an 11 year old sony in there before, so dont know if the sony radios will still have the same connector???
or, i get someone to wire it in properly!
it p's me off because i paid around £4k for the engine and boost work from a pretty major trader on this forum, and to find that they wire stuff into an iso connector is quite surprising!!!