Pay a Bill - Southern New Hampshire Health. Health (8 days ago) If you'd like to make a payment in person, the cashier's office is located near the main lobby of Southern New Hampshire Medical Center, 8 Prospect Street, Nashua.The cashier's office is open Monday through Friday, 8:00am until 4:00pm. For your convenience, you can also pay a bill online, using our safe, secure Bill pay portal..