Cam chain snapped at 96k miles, Vauxhall gave 50% contribution to repair, new head and valves, chain, etc.

106k miles rattling noise from timing chain end of engine, booked in at Vauxhall to investigate, by the time car actually goes into garage noise has stopped, not wanting to pay £200 for investigation by garage opted for oil change & filter.

Two weeks later water pump fails, get fixed by independent garage after being qouted £400 by Vauxhall garage, whilst garage is replacing pump they point out the missing bolt.

Contact Vauxhall, have to take to dealer for investigation, dealership describe what they find to Vauxhall Area Technician, explain no sign of missing bolt and cannot explain damage to chain guard, assuming if bolt had dropped into engine should have jammed chain and snapped again, because of this Vauxhall refuse to honour 12 month warranty on the repair done 6 months ago and the fact that somebody else changed the water pump !

Has anybody else had this bolt shear off after a timing chain repair. I have included picture of the various parts.