It is extremely rare for a lab to turn away a Lucis client. If you have your lab visit voucher on your phone, you're entitled to show it at the front desk and ask to speak with the lab director.
That said, your appointment may be cancelled in the following cases:
you didn't book through Lucis and don't have the visit voucher;
you didn't bring your saliva and urine samples (complete panel in France);
you didn't follow the blood draw conditions (fasting, and avoiding supplements and seafood for heavy metal testing).
In any of these cases, call us directly and we'll support you as a top priority.