I recently brought a new Audi 1.9TDI from my local Audi dealership in a London suburb. After approximately one months ownership I started to encounter issues with the diesel particulate filter. The warning light has come on four times in under 4 months ownership, despite varied journey distances. The issue has obviously been very inconvenient and the DP filter issue was not raised at the point of sale. The car has been inspected by the local service department, which have been unable to undertake any repairs to resolve the issue. Following this I contacted the dealership, which agreed to undertake a car swap. However, there is no equivalent car available, as the 1.9TDI has been discontinued. New cars of similar spec are now about £2,000 more expensive. Audi is asking that we contribute. However we can't help but feel frustrated that we will be paying more money, when the fundamental problem is that they have sold us a faulty car. Are we entitled to request they substitute the car (to the same specification) without us being out of pocket?