Water leak from apartment above

My son owns his flat in a block and part of the service charge is to cover buildings insurance. So I'd contact the managing agents and get them to make her sort the leak. She can't just ignore it and make it everyone else's problem.

Is the flat leasehold? My daughter lets her flat in London and the lease is owned by a housing association who can obtain entry to the flat above. It also means that any damage caused is covered by insurance. If there is no lease he will indeed have to get his insurance and solicitors involved. My daughter also pays an estate agent to manage the property and they sort these problems out.