Badly built building and stomping neighbours

The building we live in has eight apartments, two of which are owner-occupied. All others, including ours, are managed by the same real estate agency. We live above one of the owner-occupiers, who informed us the day after we moved in that the entire building has a noise issue as it wasn’t built properly and it would be appreciated if we walk with caution. We are therefore extremely cautious when walking around and have also put down rubber flooring and extra rugs (on top of the rugs that came with the apartment) to minimise any noise. The tenants above us have no rugs (so are walking on tiles), don’t walk cautiously and have vacuumed and hammered as late as midnight on occasion. The subsequent noise is extremely loud and disruptive and it has gotten to the point where we are questioning how bearable the situation is. We have approached them nicely a few times regarding this but their attitude has been disappointing and they basically don’t care. We’ve made an official complaint to the real estate agency and also requested that the landlord of their apartment put in some rugs but are also wondering: 1) how many official complaints have to be made before some action is taken?; 2) will we be penalised if we move out before the end of our lease even though we were never warned about the noise issues by the agency before signing?