Where can I find the location of my fuel pump relay? Does it sound as if it needs changing? I can drive the car for as long as I want when I start it up but when it needs fuel or iv reached my destination and I turn the engine off it doesn't seem to want to turn over again.

I've taken it to five different garages and the best explanation is that the fuel pump relay is to blame. It's really cheesing me off, as I've spent a lot of money on it and still haven't solved the problem.