Have you got it back yet?
I hope they don't try to charge you for the loom or the labour to dismantle and reassemble your perfectly good stock loom? That e-mail from the dealer stinks - if, when they eventually opened up the loom, they found nothing wrong, what's their explanation for suspecting it in the first place? Don't they have a multimeter?
And, as KevMean suggested, the ignition would be one of th first things to check with poor running.
Quote:
the dealer repairing it has decided it is not the wiring after all they got the bike to start but there is a lot of mechanical noise from the timing side and the rear of the cam position sensor looks like it has got very hot and there are traces of metal shavings on it. they are going to take the timing cover off to inspect further[oil pump failure maybe?]
There is no oil behind the cam position sensor (or at least, there shouldn't be), so I cannot see how they might come to the conclusion that it might be an oil pump failure. If there are metal shavings behind the cam position sensor, it's possible that the screw holding the trigger rotor has come loose. You are being fleeced. If you have not already done so, rescue your bike from these incompetent blaggers as soon as possible.