Country garden Shang real estate

How to solve this problem? Now we are faced with the problem of deferred payment. From the beginning of buying a house, we will make a down payment of 30%. We agree that the rest can be mortgaged from the bank. We recommend CITIC Bank, saying that we can't borrow that much. We got two contracts, one for the house itself and the other for the decoration. You can only borrow a house, but not a decoration loan. He also kindly introduced the financial intermediary and said that he could borrow money. I also paid a so-called financial service fee (but the payment slip says advertising printing fee). I have to repossess the building now, but I said that the original decoration payment was one month late, resulting in thousands of late fees. Now I have the building back, but I didn't give the owner the key. Found that the original sales has resigned, and even the original sales manager has resigned. There is no way to complain now, but I don't know what department to look for. If you can't get the house key, you have the right to detain it if you don't pay the late fee.