I haven't had any pre preg blood tests, but all the other ones I have had while preg have been bulk billed other than the NT tests...

I don't understand how you say that you were told there would be no out of pocket expences but you'd get a rebate from MedicarE? To get a rebate you usually need to pay for what you're having, and MC never (well, not that I have ever come across) refund a full amount unless they are directly bulk billed by your GP.