I actually owned my effected Vw privately from new, but it’s now long gone mainly as the so called fix made the vehicle sluggish and terrible on fuel.
saying that I sold it for much more then I thought it was worth.
You would need to prove the amount you were out of pocket, likely to mean you need proof of the mileage you covered and then get a sum agreed on that basis.
It’s very very difficult to prove and get any compensation at all, like all these cases anything won in court will be eaten up in league and court costs.