Hello. I'll be happy to assist you.
I'm very sorry to hear about this situation. I'll do what I can to help.
First off, there is no defamation case here. In order to make a defamation case, you must prove that they made some false statement about you that caused you some harm. Here, they are doing the opposite - they aren't saying anything and just not renewing your lease. As such, you don't have a defamatory statement. That said, defamation is not your only avenue. It is illegal to discrimiate against someone when it comes to a housing application if they fall into some protected class. This is the Fair Housing Act, which you can read about more here: http://portal.hud.gov/hudportal/HUD?src=/program_offices/fair_housing_equal_opp/FHLaws/yourrights. Under the FHA, the protected classes are race, color, national origin, religion or gender. If they are refusing to rent to someone based on one of those grounds, you may bring suit (note: they MAY discriminate based on age). Keep in mind that they don't have to admit one of those is the reason for refusing to rent to you, so long as you can prove that is the actual reason. This can be done through an analysis of their leasing applications, and who gets greanted and who gets denied. You can get access to all of that if you file suit. Of course, just the prospect of litigation
may be enough for them to renew your lease.
I hope that answers your question. If not, feel free to ask follow up questions. If so, please remember to "Rate" my answer before you go. Good luck.