Hi Alan...welcome to the Forum
Not sure regarding costs for different stitching but can well imagine it would add time to the order.
I will leave this to someone who has some experience with this to answer more accurately.
Cheers, Trevor
Ask them if they updated the emissions fix on your car. There is lots of reports that they do it without asking you and ppl have issues after
https://www.hypermiler.co.uk/dieselgate/is-the-vw-seat-audi-and-skoda-dieselgate-emissions-fix-causing-egr-valve-to-fail
Hmm well if it's egr/egr cooler that's failed i doubt Audi will want to say it's anything to do with the cambelt change and will want to replace it at a tune of approximately £1200