09 XC70 D5 auto stuck in 3rd

[Wilko66]

So I was travelling at a steady pace, about 50 mph when the car shuddered and the transmission service and dstc warning lights came on. The car is now stuck in 3rd gear but still drives. I plugged the dice in and it threw up several codes all at the same time:
TCM P171900 Engine torque signal
ECM P020500 cylinder 5 injector circuit open
ECM P070000 Transmission control system (MIL Request)
TCM P071100 Transmission fluid temperature sensor A circuit range/performance
ECM P208062 Exhaust gas temperature sensor circuit range/performance bank 1 sensor 1 - algorithm based failures- signal compare failure
ECM P030500 Cylinder 5 misfire detected
ECM P010116 Mass or volume air flow circuit range/performance- general electrical failures- circuit voltage below threshold

Plus numerous U codes relating to invalid data received from Engine control module.

Had it to the dealer, who to be fair, I thought were reasonable. Said it was either a wiring fault or gearbox solenoid. They explained they would charge me (after the initial charge of £150 for an hours diagnosis) 150 an hour and may not find the fault. Any ideas?