I think that you should have posted this in the correct Audi model section of this forum as that would have quickly given you "better/clearer" answers. For what it is worth, it is still 2017 and you say that your car is a 2017 S3, so does that mean that you have covered a very high number of miles/Km? While it is always possible to get an ordinary garage that is VAT reg'd (in UK), to do this job, I'd be sticking with Audi while that car is still under warranty just in case you need help from Audi.