Milestone Leasing & Management

I had rented from this property management company before and didn’t have a great experience, but when I fell in love with an apartment they had listed I ignored my gut and submitted an application.
On August 31, I was offered the apartment as long as I could put down a double security deposit (due to credit history… don’t judge) within 48 hours and we agreed on a move-​in date of October 1. I dropped off a check on Sept 2 for the amount of the double security deposit, as well as a non-​refundable pet deposit, and was called the next day to say a certified check was needed and that they would hold my personal check until they received a certified check in the mail.
On Sept 9, I called to inquire if they had received the official check, and they informed me that they had not, and that the tenant had decided to stay in the apartment.
When I initially looked at the apartment, the tenant was there and told the leasing agent that she had already secured a place to live and would be out no later than Sept 5. I find it hard to believe that they are being truthful about the tenant staying and have a sneaking suspicion that they probably rented it to someone else, despite having offered me the apartment. I have attempted to call the leasing agent several times today and have never gotten a return call. Previously, the leasing agent was much more responsive and available.