Following the report from your reader in your latest e-mail, you may be interested in my recent experience with my Tiguan diesel (2013 model)
It recently went to the main dealer to have the software update supposed to address the emissions problem. Prior to the update the car was running perfectly well, but after the change it started to rattle very noticeably under light to moderate acceleration along with increased fuel consumption.
Subsequently the dealer took it back for investigation,( apparently involving info from the VW factory) which took a week. (I was provided with a loan car).

This resulted in a further software modification. I got my car back a week ago, since then it has started to exhibit the same rattling and fuel consumption symptoms, Having given it what I think is a reasonable amount of time and mileage, I will report the present problem on Monday and see what the dealer proposes to do.

I will keep you updated on the progress of this matter, if you wish.