Left me with nothing

I’ve been ripped off by this company. At first I thought they are good, and they will help me. I have signed up all the needed documents to get a mortgage. I sent them the money, $3500. They informed me that everything is going swell. And later I did not receive anything. They kept mailing me and telling that the process is taking a bit longer. But it has been three months now. How much longer should I wait?