@kezo that sounds like there’s a good chance that there’s no solution without other potential problems such as even worse mpg.
As it stands, with the need to drive unwanted journeys and this aggravating my back, I think Motability will allow me to cancel the contract. But if the car is fixed in a way that the mpg worsens even more, but it prevents the clogged PPF, I’m not sure Motability would allow me to cancel the contract which would then be based on poor mpg.