What are my legal options for my situation?

My apartment complex had my car towed because I parked in one of the assigned parking spots. That particular spot is not assigned to anyone because it belongs to apt 210p in which no one lives in and I know because it's next door to me. I have been parking in that spot for about a month already with no trouble because no one uses it. The apartment complex doesn't have any signs that says assigned parking only anywhere. On the warning slip they put on my car it says that it was written at 11:15 am and that it would be towed at 11:50 am. What is the legal time frame they have to give me To move the car? If they don't have a sign saying its reserved parking what can I do? The slip they put on my car didn't have the vin on my car it only had the license plate number. It only said Honda and the color black that's about it it didn't have no signature from the office manager or other employee. What are my options?

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