Hear every footstep from upstairs

My husband and I purchased an off-plan apartment and moved in last year, everything seemed perfect at the beginning. Then my upstairs neighbour installed timber flooring in the entire apartment and our nightmare started.

Prior to the installation, they hired an acoustic engineer to conduct a test in my apartment. Based on the test, the hard flooring they installed complies with the bylaws-4 stars rating, so strata approved it. However, I can hear every footstep and some appliances working ( fan or humifier) as long as they are home. What’s worse is that they have very odd routines. During daytime the noise is bearable, but we can hear them walking around and appliance working in both bedrooms constantly between 11pm – 4am. A few times their footsteps actually waked us up around 2 or 3 am. 

We first brought this matter to the building manager, he told us nothing he could do. Then we wrote to strata manager, she said this is not a strata issue as long as the flooring above complies with the bylaws. 

We talked to upstairs neighbor, a young couple, they were shocked that we could hear them. They said they did not do anything out of ordinary and promised they would try to keep it done. Yet we can still hear them walking around 11pm – 4 am and their darn appliance working.  

These constant noises make my insomnia a lot worse and I feel so helpless. They are a young couple and kids will make it a lot worse in the near future. Considering the real estate price nowadays, we can’t afford to move out or sell it right away. Even if we do, I’m worried it may not be easy to rent out or sell this apartment because of the noise. 

Can anyone give us any advice in regarding to the noise?