"Booking blood test"

I rung up a book a blood test for my vitamin D deficiency check if its ok to being pregnant, they said I could just turn up, I said it was on GP form but said I could turn up as it was antenatal, I arrived and got turned away because it was on a GP form,I explained what I was told and they refuse to see me, so I rung up to book an appointment and they asked me questions and said I should be able to turn up but I've booked it now and have to wait till the 10th December, I am currently 32 weeks pregnant and having these checks atlee appointment for the health of me and baby! I never have any problems with this service usually and think you are excellent and keep us safe and understand you got to look after other people too but you need to help us understand as patients and communicate with the booking clerks or you are going to have more issues like this!