We know the original post is years old but we have recently encountered the same issue with our 2007 Jaguar XK. The dashboard that has the info screen regarding mileage, mph, etc. is muddled and is barely readable. Not a surface issue but appears inside the plastic lens. Did you ever get an answer how to fix or replace it that actually corrected it? Thanks for any feedback.

 

Once you have the part repacement is pretty simple. Just google instruement cluster removal for guides on how to get the thing out and strip it down. Be very careful of brittle plastics. It seems to be just a display no impact on codes or anything.
mine is still good.

 

You can see my solution in post #39. If you are looking to just fix your existing instrument cluster, there are plenty of replacement instrument clusters for sale on eBay that you can use for parts. You would then need to find someone local to you who would be able to take the donor parts and put them into your cluster.

Good luck!!

Ken