Back to the drawing board ... or to eBay. Is your car silver? There's a silver n/s/f wing on eBay for £150. It may or may not be the same as a silver one I found in a breaker this week for £185, which was cut to an offer of "£165 delivered" when I said no, wrong colour, too much.
The part code for the n/s/f (my worse wing) for the 3R chassis is 3R0821021C. Put "Seat Exeo 3R0821021C" into eBay and the £150 wing will turn up, Mouse. I'm thinking about it. But I'd need to have it sprayed blue and it's yours if you get there first.
The time from bubbling on the lip to unsightly and rusted through with holes was about two years. I have one wing that's urgent and another that's still a year or two away. Good luck!