You want people you can trust and who know the estate.
There are tried and tested service providers who have worked here for years and know all the issues with Barbican flats. They may have a lot of work on, so book well ahead to avoid frustration.
Check my Making alterations page because you need approvals for some works but not others.
For emergencies, like leaks and floods, Metwin are the City's service provider on the estate. For out-of-hours emergencies, there is a resident engineer on 24 hour call.