First of all, post in the regional section. Some of our Scottish punters might be able to list SPs who don't care about lack of feedback.
Secondly, find a WG in your area with hundreds of ratings who sees guys with no feedback and book via aw for her cheapest service. Don't tell her you're only seeing her for the feedback but remember to be extra polite to her and leave feedback and she'll do the same for you.
I had to do it a while back after I'd taken a break from punting before I got to the chance to get a meet with an absolute little stunner who was being rather fussy with the clients she'd see.