In reply to Edd Reed:
> The mechanic is family and owns a Trafic himself, the point is, 500 miles for the salesman to 'take a look', rather than just authorise me to let a mechanic here do it.
> The fan speed thing is a common fault and is the resistor pack (£70), the intermittent panel lighting could be the switch pack (£120) and about £40 labour plus VAT on all of the above.
> If a part does not need fitting it wont get fitted and will be returned.
> I will quite happily get other quote but they will cost, for instance the local Renault dealer will charge £80 plus VAT to just take a look.
It's a tough call, but if I had sold a van is be nervous of deferring the diagnosis to a friend of the purchaser who was submitting guessed at quotes based on common problems they know of.
I can see why they might want to do the job themselves and wonder if this was a choice you made when you purchased from someone so distant.
Could you get them to nominate someone that they would trust to do the work closer to home for you?
Personally I've always worked on the theory that such electrical glitches are a fact of vehicle ownership and if the fault wasn't apparent until several months after purchase I just get on and fix it myself.