super annoyed with doctor's ughh

so I'm 28 weeks and 5 days. two weeks ago doctors gave me a prescription paper and told me to go to the lab to get my glucose test done, to just ask for a walk-in (there's a lab at the clinic I go to) I procrastinated honestly as work has been exhausting and I've been so busy. I wake up yesterday and go in only for them to tell me the prescription is for a completely different lab I've never even heard of so I can't be seen there at the clinic. so I google the lab and it's like 14 minutes away by car. I have no car or money for transportation. so my husband's father says he can drive me there tomorrow and I'll be nearly 29 weeks. they also had said at my clinic that I can just go for a walk-in so I'm wondering if I should call prehand to make sure? I'm just pissed my doctor's didn't just give me the prescription for the lab that's already in my clinic! ughhhh