Power button fault (car engine continues to run, unable to turn off)

[mik786]

Our Focus ST 2010  has developed a fault where the car fails to turn off after some journeys when the stop button is pressed.  The only way to stop the engine is to stall the engine.  All the power lights remain on and the keyless fob doesn't operate the locks or allow the ignition to be restarted.
I have included a video of the fault below.

Sadly Ford main dealers have been unable to fix the issue despite having the car for six weeks and changing the main control unit, power relays etc,  which cost over £600.  

Does anyone have any idea what may be causing this?
If not does anyone know of a reputable Ford Auto electrician in the south of England that may be able to help?

Thanks,
Imran
Berkshire UK.
 

[dezwez]

is the switch working ok or is it naf

[WES180]

Surely they changed the switch too? Id have thought that would have been the first thing they changed if they were just going to throw a load of parts at it.

This Focus had the same symptoms but it turned out to be a software glitch.

https://www.fordownersclub.com/forums/topic/88463-focus-engine-will-not-turn-off/

Major problem in America too albeit newer models

https://www.theregister.co.uk/2015/07/02/ford_recall_software_bug/