fitted by a Vx. trained technician
Why are alarm bells ringing in my head when I hear that 
I agree, normally Vauxhall training would be a bad thing, however this chap seems to be a good mechanic despite their best efforts.
He probably could have completed the job in 2 hours but he kept stopping to explain stuff to the cars owner, like the importance of regular oil changes!
I'm a fairly competent d.i.y. mechanic with a near full set of tools and I have always managed to keep my own old bangers on the road without having to pay others to fix them, I was going to replace the chain on my friends Signum for him but considering the cost of the chain, and how long it was likely to have taken me to do the job (also the 'Renault incident' had knocked my confidence a little!), we decided to try some-one else...
Have been looking through the history file and found the cost of the camchain kit, It had a full service,camchain kit,front brake pads,service filter pack (whatever that is ) tail light bulb.screen wash,
semi synth oil,
spark plugs,
air freshener, 
2 x front tyres.
And wait for it £866.54p
I'd say the invoice was a good few years out of date, that seems cheap.