Part of your P&S is a mortgage contingency. If you cannot get the mortgage by the specified date, and you have done everything that YOU can do, legally the RE company cannot keep your down payment. Check your P&S wording and the dates in it. Check the financing contingency.
If you need any further help, feel free to contact. Thanks, and good luck,
I would suggest the following, if you do not trust your real estate agent then go directly to the office broker and state your situation with your real estate agent and have the broker submit a closing extention to the seller allowing you to close at a later date. Coordinate this with your new lender if you decide to switch or you may want your closing attorney to get involved and contact the lender directly to see if he can get to the bottom of the problem.
hope this helps, best of luck.