Citroen C1 fault code P0010, ideas wanted

[MrJambon]

The story so far.
I have a 2010 C1, with variable timing. The engine management light is on and its giving me the code P0010, Camshaft sensor /actuator open circuit bank 1.
What I have done so far in the last ten days.
Two engine oil flushes and new oil and filters (no change)
Bench-tested the camshaft position sensor, crankshaft sensor and camshaft actuator, they all passed the parameters given by Haynes autofix.
Even though they all passed I've replaced them with new replacements.
I've traced the actuator wires back to the ecu and there is no open circuit on the earth side and there's power to it.
I've cleaned as many earth points as I could find, all work carried out has made no difference.
I haven't owned a C1 before so I cant compare how its performing but it does seem to be fine, slightly underpowered but I dont know if its normal as I have no reference.

What do you all recommend I check next, my son has to take his driving test in it in one week and it will be terminated if the light is on even though the car performs ok.
Help and advice urgently required, thank you.

[Huskyxantia]

Cam timing issues typically occur during higher revolutions per minute (RPM) of the engine. This is when the powertrain control module tries to adjust valve lift during higher speeds.

Note: The Variable Valve Timing solenoid valve is also known as the camshaft actuator solenoid valve or oil control valve (OCV.)

[Huskyxantia]

Sounds like an engine that needs a good flush.

[Huskyxantia]

Had a google and its confirmed some of my thoughts to what it could be heres the findings

common causes of the P0010 code:

An internal failure of the Variable Valve Timing solenoid valve (in other words, a stuck oil control valve)
Crankshaft sensor malfunction
Camshaft position sensor malfunction
Excessive engine oil sludge (from lack of oil changes)
Contaminated engine oil blocking the Variable Valve Timing solenoid screen
Engine performing outside of proper timing parameters
Engine timing is out of sync
A worn timing component like chains, gears, and guides
Internal damage to the Engine Control Module
The Engine Control Module software is out of date
Circuit problems like damaged wiring or poor connections (e.g., bad ECM connector)

[MrJambon]

cheers. i have eliminated the first five. its had two good flushes and two filters when flushing. new timing actuator even though it bench tested fine, camshaft an crankshaft position sensors changed, even though they also bench tested ok. ive followed the thirteen electic/electronic diagnostic checks suggested by autofix,. i am at the conclusion that the timing chain is streched, i have physically inspected it today, the top-end timing marks were okay but i know i have to check them when the crank mark can also be seen. there wasn't much movement in the chain, but i can't find the tolerances anywhere, perhaps my idea of not bad is way off. I think it needs a chain, I was just hoping someone would suggest a relevant test that i haven't tried. Dont really want to put a timing chain kit on and it still be the same.
Thanks for your suggestions.