What Can We Do As A Last Resort If Property Management Won't Fix This Fruit Fly Infestation?

Location: TN

So this is a strange situation so bear with me. My fiance and I have lived in this upstairs apartment for 9 years. Never had an issue until last summer. Our old neighbors moved out, they cleaned up the apartment, then new neighbors moved in. We've never seen these neighbors and as far as I know, they're still "renting" but no one lives there. They have some legal notices up on their door and a fedex package that's been there since November.

We also had a tornado sweep through around this time last year that caused a lot of damage to our roof. They fixed the outside but I'm not sure if there's more damage elsewhere that we can't see.

Those are the only two things that have changed in the 9 years we've lived here. The storm and those neighbors. And these fruit flies are absolutely out of hand. They are taking over our lives and destroying our sanity. My fiance is up at 3am cleaning and sealing drains and vents.

Before you suggest tips for fruit flies, we've tried it all. Apple cider vinegar traps, light traps, tape traps, sprays. We have every drain in the house covered. In addition to that we run boiling water, chemicals, and a vinegar/baking soda mix down the drains daily. My fiance caulked all the windows and doors (we had a work order put in but after a few months he just did it himself. It looks really nice). We still have a work order to fix the screens. We don't eat in the house anymore and don't keep food anywhere. We either eat out or in our cars. We take the trash out every day as well as the litterbox. I've stopped watering my plants regularly to avoid damp soil but we had the flies before we had the plants.

My issue is that it doesn't matter what we do or how hard we fight it, if we don't get to the source they will never be gone, and we don't have the power to get to the source as renters. They're either coming from some spot of moisture where the roof got damaged, our AC unit that is leaking in our storage unit (we have a work order for that too we remind them of often), or our neighbors. I'm thinking the neighbors is a high likelihood. If you walk past their windows you can just see the flies. The whole complex has to be overrun but no one is living there to report it. My fiance and I joked that someone might have died in there, but if that were the case I think there would be an obvious smell and house flies as opposed to tiny fruit flies.

They keep sending pest control but even the pest control guy said his spray wouldn't really work on flying insects. I went to the property office yesterday to talk to a supervisor face to face, just to get someone to really understand what we were dealing with. I explained EVERYTHING and showed her videos of the leaking AC unit. I even told her about the trash and bucket full of water sitting out back of their place that my fiance tried to dump out, but the bucket started disintegrating and was full of parasitic looking worms. She said she would have someone come out and do a scope of the downstairs apartment, put in another work order for the unit (which she apologized and said they were very short staffed), and also said she'd send out pest control again...

I'm hopeful, but at the same time I don't think anyone can understand how insanity inducing this is unless they're living it. My fiance has spent hundreds of dollars on trying to manage this infestation. He's considering moving but that is just so messed up to me. There's got to be something more we can do.

In the event that nothing comes of this conversation with property management, is there anything we can legally do to get them to actually fix this? Aren't landlords required to act if a dwelling becomes unlivable? Would the cost be worth it or is moving really our best option? I just feel so defeated... Even as I'm writing this I'm being bombarded constantly by little flies...