Can you try this ?

Buy a fan. Instead give it to your neighbor, turn your fan in your room all night. Your fan is very smooth, which will cover the low frequency noisy from above.

I rented an apartment on the top level of a building before. When summer came, I found out there are a few air condition units on the top of the building, just above my bed room. I almost went crazy. Then I turned on the fan in my room the whole night, which helped me to almost solve the problem.