Why exactly did you "fail" the PFL part?
When I practise PFLs (not down to below 500' and never in the same area I might add btw), I certainly can't be 100% confident I would have made the field all the time. This surely does not justify a partial pass in a skills test surely unless you had not shown any evidence of what you had been taught? In other words, I was not under the impression it had to be obvious you would have definately made a safe forced landing from the 500' point in the particular field you were shooting for? moreover it's a question of demonstrating a good pattern, maintaining glide speed, decision to use flaps, checks, RT calls and so on.
Any instructors care to comment on this?