[Closed] Insurance replacement camera - advice please?

A while ago I had my Canon 350D stolen. It had an upgraded lens on it which I bought S/H off a mate for cash so no receipt.
The camera is covered (cos I found the receipt) but they'll only cover it for the original kit lens it came with and I also don't have receipts for the expensive memory card that was in it. 🙁

So they phoned up today to offer me a Canon 1000D with kit lens. I asked if I could upgrade to the Canon 50D, they said yes for an extra £465.

Do I need to accept this given that a 50D is £940 with lens? Can I just ask for/demand cash? Can I negotiate a lower price?

I guess this is a lesson to *always* keep receipts...