At best they may be able to measure the chain for stretch/check for wear and see if it's within allowable limits. Timing chains normally break very quickly with no warning of failure.
I guess you could see about getting your timing chain assembly upgraded to the latest spec
If you want to know more about your engine you should get this manual from GM
The cause of the chain snapping is due to lack of lubrication due to the chain spray jet blocking up. The jet is a tiny plastic jet with a pin pr1ck (Sorry - won't allow me to use correct grammar!!!) hole in it located near the simplex chain guide at the lower half of the block.
Vauxhall have concerns with the oil filter breaking up and sometimes blocking this jet
At the moment there is a recall on these engines - which involves changing the chain, tensioner, guides, cam sprockets and oil jet etc