I presume you'll be finding a new optometrist for next time. I would have refused to pay, since they weren't giving the full service. In Australia the eye test is covered by Medicare, so if they refused to supply it you could complain to the government insurer and there would be trouble.
According to my optometrist, the PD measurement isn't part of the prescription. The prescription documents the lens, the PD is needed only for glasses.
