ok I tried a new relay and no buzzing but dead so reading about the fuse suggestion I set about removing and testing every single fuse once again (it was one of the first things I tried).
I found a 20 amp dead fuse and low and behold everything seems back to normal. I must have missed the only dodgy fuse the 1st time round doh! I haven't tried the stereo yet as I'm at work but fingers crossed all will be ok.
Thanks to everyone for their suggestions in this thread as I was close to giving up..
To say I'm happy is an understatement as I was thinking id wrecked the ecu.
Now to crack on with the rest of the problems my omega has, you lot will be sick of me soon

Thanks again...