Thanks for the useful replies.

Having looked through my booking history it seems that none of my 18 bookings and well over £3000 of expenditure have been acknowledged by Avis since the scheme changed (think it was May 2012???) and I have now sent them a lengthy email with all my bookings to sort it all out.

I suspect they will try and do all they can to avoid giving me my rightly earned Avis First Plus status!