How much should I be looking to pay to sort out a Scart problem?

I have a Toshiba 33in TV (about 8 years old). It's huge and would be really difficult to dismantle and get in my car.
There are 3 scart inputs - 1 works fine. However on Scart 3 the sound has gone, and on Scart 2 the picture has gone funny - very dark and colour is intense. I think this happened when I plugged my X box into my scart 5 to 1 adapter at the same time my sattelite receiver was plugged into it.
I am in Northwest London and need to get someone round to fix this. Can anyone give me a ball park figure as to how much this should cost to fix, and is it an easy job.
Any help would be greatly appreciated.
Cheers
Andrew
aony25@dsl.pipex.com