John,
I have been an MVRA member for for about 8 years. We use their helplines regularly and find this alone worth the money. They do try to find whatever information you require and will fax wiring diagrams etc swiftly to you.
About six years ago we fitted a brake master cylinder to a BMW. The customer was from Oxford and only in Scotland for a funeral. On his return home he suffered brake failure. He telephoned with threats of various legal actions if I did not fix his problem. I contacted the MVRA, who uplifted his car, took it to a nearby member, and arranged an inspection with the customer present. A failed rear wheel cylinder was discovered. We should all have some sort of back up i.e. be a member of something with resources and clout,
Tom