Broken cam belt on recently purchased car

I bought a Daewoo Kalos from a dealer 10 weeks ago and the cam belt has broken. Where do I stand with the dealer is it to late to go back to him?

Cam belt intervals on an Astra 1.8?

I am looking to buy a 2007 Vauxhall Astra 1.8 Sri Vendor says cambelt does not need replacing until it has done 100,000 miles as it has a Se engine. Is this correct?!

When should I change my timing belt?

Can you tell me when I need to change my timing belt as I've only had the car for three weeks and its done 90,000 miles.

Should the dealer replace my cam belt?

I bought a Citroen C4 Picasso 1.6hdi vtr+ 2 weeks ago from Arnold Clark Northwich. It's a 57 plate Picasso with 39,000 miles on the clock and I have noticed a chirping sound like the cam belt maybe slipping....