Thanks all for the responses. I checked out the Montreal Convention, looks like max $2000 compensation but I didn't see anything regarding receipts.

I understand the fear of outlandish, unscrupulous claims, however, I'm claiming for reasonable items - just my clothes. Not gold bars or violins. My initial goal was just to get my items back, I don't even want the money. I'm only claiming compensation now because they were unable to return them back to me. Unfortunately money can't replace my exact belongings, but Swiss, not the PAX, should take responsibility for their negligence.

I'm fed up and have passed this on to my company's travel and legal teams as I was travelling for work, they can probably get further than myself as an individual. I've spent too much time on this already!