One of my previous cars once stapped a timing chain, the effect is the engine loses it timing and can cause terminal/severe damage to the engine, if that has happened and you have lost compression it could be a majour engine rebuild. Its unusual though, an engine of that milage and service history, i would expect the chain to last the life of the engine easily 100k +. I must confess I thought this was fuel related, i.e. fuel pump or perhaps fuel filters but the filters should of been changed, so maybe just the pump. I commented on your other post. You could contact the garages you have sent it to and ask them if they checked the timing chain ?. Sorry I can't be more help Richy.