Email them...they should respond (they did with me)
The information is not on the website, but if you email them, they will get back to you. Email them, identify yourself as an initiate of _____ Sorority, and could you please have the contact information for the Alumnae Panhellenic Associaition for _____ City. They should get back to you (or just phone them).
I asked them once about an Alumnae Panhellenic in Australia and they got back to me with the response the same day....