<p style=”text-align: left;”> It has juddered and been hesitant since just after the 14 day cooling off period……………</p>
Just so you are aware, there is no ’14 day cooling off period’ with a Motability vehicle.
The Distance Selling Regulations do not apply, as Motability insist that you collect the vehicle from the dealers premises (even if you can currently order remotely).
Once you enter your pin at the dealership there is no right to cancel or return the vehicle, you are bound by the lease agreement. The following is from the Motability Lease agreement:

By entering your PIN when you collect the vehicle you are agreeing to the t&c’s of the lease agreement including the above.
However, if you can demonstrate to Motability that you have lost all confidence in the vehicle due to a recurrent (and seemingly unrepairable) fault, Motability, as owner(s) of the vehicle, may permit you to terminate your lease at their discretion.
Alternatively, Motability as owners can reject the vehicle, but obviously this must be done in co-ordination with Motability (as they own the vehicle), the leasee and the dealership.