Of course it could just be that it is summer and the teaching couple is on vacation. They just teach at the hospital which is why information wouldn’t know anything. See if you can get a hold of someone who schedules the use of the classrooms at the hospital - they might have more information.
If none of the suggestions already posted work then wait patiently for a couple of weeks and call again. Answering machine messages get erased (I know, I have done it by accident myself when the message was important to my business!) My understanding is that most NFP classes are taught by teaching couples and it is usually their home number you call to get the information and sign up.