If, however, your agent is not proving you with good service, then you would need to speak with the broker at that agency to resolve any issues that you may have with your agent.
Kathy Persha, Realtor
Keller WIlliams Realty
I'm going to assume the Listing Agent 'refused' to talk to you because you are working with your own Realtor (representing you). If that is the case, have your Realtor call the Listing Agent and that should solve the problem. If it doesn't and the Listing Agent 'refuses' to talk to your Realtor, have your Realtor call the Listing Agent's Broker.
Short sales can take a lot of time, depending on the circumstances. Have you talked to you agent about this? They should be able to contact the listing agent and if not, contact their broker.
Good luck, it will be worth it