If you're unhappy, I would reject the vehicle while you can. You only retain the right to reject the car if there is something fundamentally wrong with it. But you can reject it within six months of the date of purchase. This includes faults that were present - or developing - when you bought the car, or it was received in a condition that does not match what you were told.
I would suggest rejecting it if you can while you still can because we've had reports of ongoing issues with this engine despite Volkswagen saying they have no further plans to update software. You rights can be found here: www.honestjohn.co.uk/how-to-reject-a-car-your-cons...s