Is this against tenants privacy rights? If so, ADVICE PLEASE!?

I live in an apartment complex in TN. I recently had surgery and ALWAYS make sure I lock my front door when my partner is at work. I wouldn't be able to fend off an intruder if need be. Anyway, this past Saturday after my partner left, I locked the front door and jumped in the shower. Ten minutes later, I heard a VERY loud banging sound right before I got out. I put on a towel and walked into my living room. The very first thing I did was check the front door, which I found to be unlocked. I then proceeded to look out of my windows to see my maintenance man, running like a madman to his truck. He got in, then took off like a bat out of hell. I locked the door again and called the office. I didn't get anyone directly, so I went down there. The associate who was there said she did receive a plumbing work-order for apt 305 and he could have gotten the numbers mixed up, despite working here for the past 20 years. I've worked in property management and said I can totally understand that. I then asked her what type of problem 305 was having. She said 305 didn't have any water pressure, that the maintenance man was POSSIBLY checking my unit to see if this was the cause of the problem OR, that he was "looking for something else." Thinking this was odd, seeing as 305 isn't on my side of the building, I said okay, I just wanted to make sure he just wasn't coming in just because. She then said, he always knocks and announces himself before coming in and never enters without your permission, or if you are not there. Okay, but that is exactly what happened. I didn't answer my door or give him permission to enter and he did anyway, while I was in the shower. 305 is WAY down the hall and is directly across from 306. Wouldn't it have been a little more logical to check the closest units first, instead of one that is 3 units down? If this WAS the case, why did he slam my door, leave it unlocked, speed off in his truck, rather than waiting outside my door for a couple of minutes and then re-knocking, to check my unit? There are over 250 units in my complex, split between 7 buildings and he just decided to check mine just because? That and he was possibly looking for something else? Like what? I'm not buying it. This isn't the first time I've come home to an unlocked door, while everything in my apartment is either on, or things were thrown around, but never taken. They said they can change my locks, but what good is that when maintenance would have a key? My mom said to put a chain latch on the inside to use when I was inside, but that wouldn't keep anyone from coming in while I'm gone. I looked into tenant privacy laws in TN, while no specified times are listed, it did say the landlord or other persons cannot enter without permission, unless it is an emergency situation or at the minimum a 24 hour written notice. Fire, severe water leak, extermination, etc. What do you think? This definitely seems illegal to me. What would be the best way to prevent this from happening? Worst case scenario, I'll have to pay almost $600+ to break my lease early. I've lived here for a little over two months.