Ford Focus engine management problem

In December 2010 when on a motorway journey I broke down, with a loss of power and engine light coming on and no sign of over heating. The cyclinder head and pistons were fried which resulted in me having to refurb the engine (as just out of warranty and second owner, no help from Ford). I got the car back and the engine light was still on, after 3 separate diagnostic checks (all showing camshaft sensor) this has been replaced and still not sorted the problem. It is now in a dealership garage and they can't find a fix to the faults it displays, the latest thinking is around the throttle. I have been without transport now for 3 1/2 months and am no further forward please help, anybody.