Who must pay me back for overpayment of rent?

We have been living in a rental home for the past year. In December '12 we wished to prepay our January rent as we would be away when it was due. We were notified that the home was being sold from the real-estate company to our property manager and his partners. We asked our property manager who we should pay the January rent to and he said to pay the contact at the real estate company per usual so we did. January rolls around and the sale of the house closes and our property manager-now our landlord-asks for January rent. We tell him we already paid the other company per his instruction. He asked us to pay him the rent for January and to go after the old company for our money back. 7 months later after trying to get our money from the company, they have sent us a check for less than half of the balance outstanding and said that our landlord owed them money and to go after him for the balance. How do we get our money back and who owes it to us? The real estate company is now dissolved.