Just a quick outcome and hopefully my last post on this subject, after a lot of research into the potential issues and longevity with the DPFs on my car I decided to keep them! There doesn't seem to be any specific cases of failure on this engine so long as the car is services properly, but if there is then I will probably get them cleaned or replaced rather than removed because of the potential insurance issues of exhaust "modification" and required re-map.
I had both sensors replaced by a local independent VAG specialist and all seems to be back to normal. Total cost £290 in the end as I needed to get some exhaust clamps replaced too.
If anyone is needing work in the Manchester area I can highly recommend VAGtechnik, they did a good job for a much more reasonable cost than any other dealer/garage I tried and didn't just make it up as they go along like the main dealers seemed to be doing!
