I would email the theatre or its box office to find out. That's how I do it when it is not advertised.
"The sexual energy between the mother and son really concerns me!"-random woman behind me at Next to Normal
"I want to meet him after and bang him!"-random woman who exposed her breasts at Rock of Ages, referring to James Carpinello
That's why I never call a box office. The box office never picks up and if they do, often they are rude when you ask about rush seats. Sending them an email to a theatre will get you a timely, accurate, polite response regarding rush seats.
"The sexual energy between the mother and son really concerns me!"-random woman behind me at Next to Normal
"I want to meet him after and bang him!"-random woman who exposed her breasts at Rock of Ages, referring to James Carpinello