Just checked other Consular offices in Cancun & Coz....they too have Monday to Friday hours only.
Below is the office info...as far as I know Samatha Mason is still the US Consular.
Consular Agency Playa Del Carmen("The Palapa," Calle 1 Sur, between Avenida 15 and Avenida 20, Playa Del Carmen, Quintana Roo, Mexico).
The U.S. Consular Agency in Playa del Carmen is open for business Monday through Friday, from 9:00 am to 1:00 pm. Please make an appointment by calling the office phone during normal office hours or send an email to: firstname.lastname@example.org
containing information about the service you require, your contact information and a preferred time for your appointment within normal office hours. Emergency cases are accepted as walk-ins.
011-52-984-873-0303 (direct dial from the U.S.)
202-370-6708 (Vonage dialing from the U.S.)
01-984-873-0303 (dialing from outside Playa Del Carmen but within Mexico)
011-52-984-873-0481 (fax dialing from the U.S.)
For a Google Map (Click Here)