If letter not fake the involved parties should answer some questions as it claims to happened at your property at the time. The police responded to the call as well, probably someone realised that the identity used was fake. The buildings these days have walls as tinfoil, noise comes from everywhere, heck recently visited a place where plumbing really needs attention as the pressure on upper floors was going ballistic loud when triggered by anything using water by anyone in the building. Identity mixed up is a concern though, I would def check whats up if I were you.