730i brake lights stuck on

I have a 1994 730i e38 and it is great except for the brake lights are stuck on. No warning messages, the dignostic system can't detect it and they haven't a clue at my local BMW dealers. They wanted £75 per hour + VAT + parts to have the apprentice check all systems ( the diagnostic already says no problem present!) and he knew less than me. Their idea I think is to keep replacing parts until it's fixed and I can do that at £0 per hour plus parts. It's not the switch, I have checked and all connections are fine and uncorroded. Light control unit? Don't want to buy one at £250 and find it's not. Anyone have any clues?
Thanks, It's a great car but this is driving me nuts.

When you say not the switch, are you referring to the stop light switch? I have seen ones that look good (ie my 750) and actually were bad. Also, you may be able to adjust the brake pedal (lock nut on threaded brake pedal rod) to keep the pedal arm from the stop light switch. I had to do that on my 750 after repalcing the switch, the pedal arm was keeping the projection on the switch from fully disengaging. Hoep this helps and you can understand my colonial english.

Richard LaBarre