When you say you "own" the flat, do you mean you have a long lease? If so, I would advise you to look at your lease, and ensure that you have kept within its terms. For example, does the lease allow you to sublet the flat; to lift the carpets; and does it say anything about not causing a nuisance (including noise) to other lessees. Only if you are quite sure that YOU are on firm legal ground, should you consider going to law. Otherwise, you may find you have bitten off more than you can chew.