Nashua Central
Ugraded and paying with no delivery of goods

I upgraded my cell contract in beginning of Jan 2013. I received a faulty I-phone 5 and return it immediately. I was told that I would receive a new phone from the new batch which will arrive soon. last update was that they are repairing the faulty phone which was supposed to have been brand new. Management does not even come back to me when leaving messages. what do I do?