Having recently been told by my local garage during a routine MOT that my back box has corroded and needs replacing I thought I would have a ring around local garages and find the best price.  To my amazement none of the garages stocked them and only one garage said they could source a replacement at a cost of £180 but would not come with the tip (which they could not source).  Surely I cannot be the only A1 driver who has needed a replacement?? What are other peoples experience of this? Is going direct to Audi the only answer??

That's annoying, but eBay is your friend: 

https://www.ebay.co.uk/itm/Audi-A1-S-Line-2015-1-6-Tdi-Complete-Exhaust-/154460824862?_trksid=p2349624.m46890.l49286 

https://www.ebay.co.uk/itm/Exhaust-System-Muffler-End-Pipe-Audi-A1-Sportback-Facelift-8XA-1-6-Tdi-/324594500642?_trksid=p2349624.m46890.l49286

I'm having the same problem atm, really struggling to find a replacement, and any that I've found have been out of stock, and any enquiries ive made, the garages are unable to locate any! I'm at my wits end with it, what else can I do? Amy advice is appreciated.

Welcome Kerry,

Try Parts in Motion at Exeter. 
Perhaps you could let us know how you get on. 
Kind regards,

Gareth.