US interview at somewhere not an airport when entering?

I am renewing and seemingly randomly ( my wife renewed at the same time and was approved with no need for an interview) I had to do the two interviews. The YYZ Canadian interview was so easy - simple booking process, I just showed my passport, in and out in 5 minutes. When flying back to the US via YYZ it was a mess. The 'take a number' machine had nothing in it , so it was just a honor system. People were just giving up after 2 hours to make their flights. I waited 1.5 hours, an CBP officer came by, just said he was checking on us while he went to get his coffee ( nice for him!) and said a "difficult interview" was holding up everything. I had to bail to get my flight.

Anyway, I have no international travel planned for a long while and wanted to do an interview at a land crossing ( e.g. Otay Mesa). But my TTP page gives me no option to schedule my US interview. I was planning on calling to get an interview but anyone had luck doing this?