In reply to windjammer:
Try either contacting Rab direct or going to their factory store if you live close enough.
They had their annual winter sale in the warehouse just before Christmas. They had loads and loads of shell jackets in XL and XXL, in fact just about pretty much every jacket was in these sizes (much to my frustration as that's not my size!)
All the items in the sale were brand new, not faulty or seconds in any way. I eventually found two shells that fit, a Latok alpine which I got for £100 (RRP £220) and a Demand Pull On for £80 (RRP £150 I think).
All the stock which didn't sell will be in the factory shop now and they will definitely still have stuff in those sizes.
From experience you can drop them a line, tell them what you're looking for and if they have it there they'll get in sent out the same day!