At last - after waiting a week and spending two hours doing more focused waiting in the Sertracen offices - I have a card that shows me, Dewitt, Susan Vera, as owner of the PazSalud car.
Easy to see how my name got scrambled. Any Spanish speaker looking at the name Susan Vera Dewitt would most likely assume that I was Vera de Witt, Susan - that my maiden name was Vera and my married name was Witt. That's how names are constructed in Spanish speaking countries: everyone carries two surnames. For men and unmarried women, those are the father's last name followed by the mother's last name. So because my father's name was Dewitt and my mother's name Hahn, I really should be, in a Spanish-speaking country, Susana Dewitt Hahn (and Dewitt is considered the main last name, el primer apellido). A married woman uses her father's name followed by de and her husband's name. So if I had married someone named Jones, I would be Susana Dewitt de Jones.
This difference in naming leads to endless confusion - the mixup of my name by the authorities at Sertracen, the mixup when Norteamericanos assume someone's mother-name is their real last name. Messes with your assumptions. A healthy thing, even if it leads to long, long waits in line.