rule: your automated phone system should never just hang up on a customer. they should always have the option to go back to the main menu, talk to a real person, or hang up themselves.
Countless times, ineffectual automated phone systems have tried to tell me information that I didn't need, then hang up on me. I have always called them back and pressed lots of buttons until I talked to a real person. I do not need to know all your hours and return policy and what your cat ate for lunch for the past five days BEFORE I press any buttons.