This is the final report, fix and solution to what happened, hopefully if anyone else as a similar problem this may help.
So as quoted in my previous post the mechanic changed the valve to the heater matrix and also changed the coolant in the system, the damage to the valve was caused by a...
@ AndyinOz
He's had no error codes showing up, he also managed to get a friend to call in from a Mitsubishi dealer that also connected there diagnostic machine and that also showed no Codes.
@ littlescrote
Thank you for your reply I have forwarded that info you have given me on to the mechanic...
Any help or advice would be appreciated.
2 weeks ago my Wife's mitsubishi outlander phev heater system stopped working, basically no heat coming through, so we took the car to our local mechanic who said there's a possibility the heater matrix is not working, but later that day he phoned us...