Non refund of security deposit

I am UofM student and was on internship in St. Louis, MO for summer. I paid $500 security deposit to the apartment complex and monthly rent was fixed.

I paid every months rent on time and vacated after three months without breaking any lease clause with proper notice in advance, move-out inspection, and cleaning the apartment to best of my abilties (exactly in the same condition as given.) Now I am back to MI.

According to MO securiy deposit staute, the landlords must return security deposit within 30 days and was also mentioned on my lease. They haven't returned it by now (46 days elapsed) and have provided no explanation. They do not even come on phone (which I have tried several times and left several voicemails) and if they come they do not respond appropriately. I am completely pissed off. I am based in MI which is not a close distance from St. Louis that I file in small claims court.

I need some advice how should I approach it now. The apartment complex is Plaza Square Apartments.

[OHlandlord]

Send them a demand letter for your deposit stating that they have passed the state deadline to return this deposit. Quote the state statute for them. Let them know that if they don't return it in full immediately that you will file to recover your deposit and 3 x the deposit in damages for failing to follow state law. Send this to them by certified mail, return receipt requested, and keep a copy. Hopefully they will comply. If not, your only option is to go back to MO and file in small claims court. In some places you can file online, but you still must appear in court for the hearing.