If your friend is in the AA,RAC or has an insurance company Breakdown Cover Scheme,contact them for Help and advise.
If i'm reading this correctly,the Chain snapped 100 miles after the Service,taking the Gearbox out and costing £2000 for a recon Engine.I would have hoped he nailed the Dealer that did the Service for the cost of that one.
The second incident seems to be a dealer(the SAME ONE ??) being asked to do a "Levels and chain check".This was presumably charged for and no report of a worn chain being given.For the chain to be eating into the centre stand with only 200 miles use from the "check" seems to suggest that the Dealer has some explaining to do.If the Job Receipt details work carried out,i hope it also has the Mileage on it ? Get the Mileage showing now, recorded by an impartial witness who can be relied on to give evidence of same.Best bet would be a bike shop who could also assess the damage.Let the dealer know what has happened,give him the opportunity to inspect and make good the damage.If he doesn't want to know,suggest you will take it up as a Small Courts Claim-or whatever the Scottish Law equivalent is.Keep right on your side by not getting shitty with the dealer if he initially stalls,the Legal threat might just soften his stance where a row will be of no consequence to him.Hope this is of help,the next suggestion would be for your friend to find a dealer he can rely on with work.
A lot of people will suggest learning basics Mechanics,which is fine if you have an aptitude for that.There might be other factors which might prevent your friend taking this route.I have been critcised for my stance on this.I don't work on my bikes for the same reason that i don't take the back off the TV or Computer.It is not my line of work,let an expert at it.I have been lucky in finding workshops that have always done what i have wanted and have never let me down.I have Carole Nash Insurance with Breakdown Cover and always have a Mobile phone with me .I don't do "Abroad" so i can get away with this slightly "easy option" attitude,but,it works for me.