I have a Fiesta 1.6 Si (Zetec model)

A while ago I finished work and the car wouldn't start, I thought I'd run out of petrol, but I hadn't. When the RAC turned up he unscrewed the rear bench and wiggled the wire, something to do with the fuel pump/line. I then got the familiar buzzing sound and the car started fine. It's happened a few times since and I've just wiggled the wire and it's started. But now wiggling the wire doesn't do anything, there's no buzzing noise, I've checked the fuse and it's not blown, any ideas?

My cars stuck outside my house and cannot be towed, anybody a mobile mechanic or know a reputable one in the Essex area.

Your help in this matter is much appreciated.

Thanks