"Booking confirmation of a SHA++ Hotel booking and a required RT-PCR test at the hotel. Passengers must stay in their booked accommodation until receiving the test results within one day."
But at the bottom for "Fully vaccinated" it should say (as it does for unvaccinated): "Passengers who do not meet the above conditions".....
In all fairness, if you showed them the current Thai Embassy instructions and they still refused you, they are arseholes.