Hi Tony,
just tried to post a reply to you and seem to have lost it, will try again.
Difficult to remember how long arbitration took, it was around 1980. I dragged it out to wind up the builders as the arbitrator told them on more than one occasion, that I must be given all the time I need as I was a layman. I researched into the testing of the product and even spoke to the guy who had done the original testing at Princes Risborough. What I did clearly impressed the arbitrator as he awarded costs, which at that time was unheard of. My original text also explained my repair technique, I'm not going to repeat it now but if anybody wants to know, I'll spell it out.
Good luck with the claim.
Regards,
Ian.