I have a 2003 Corsa 1.0, that has destroyed its engine. When starting up the engine one morning, there was an unhealthy noise and a loud knock before the engine died and wouldn't restart. I took it to a local garage who had a quick look at the engine and saw that all of the spark plugs and valves were damaged and suggested the timing chain had slipped to cause the problem.

Eight months earlier it had had a lot of work done at a different garage, including amongst other things a new timing chain. Seeing as that would be under warranty, I took the car over to them, but unsurprisingly they have come back to me saying that the timing chain hadn't snapped and looked normal. Instead they say that it looks like one of the fingers off the camshaft appears to have broken off and jammed everything up, but it'll cost £400 in labour just to look into that by taking the head gasket off.

I don't have much mechanical knowledge, but is it plausible for the timing chain to slip and cause damage to the engine and the camshaft or does it have to snap to cause the problem? Is it likely for the camshaft to break in the way the garage suggests? Any advice about what to do next - I'm thinking about getting an independent report to see if the garage is liable, because otherwise its not going to be economical to repair the car.

I'd be grateful for any help!