Will it really necessitate the shutting down of the supply to the whole block? Has ze been measured at all the other flats to confirm it is not just a bad connection at your flat. Did the tester check that your earth cable is correctly connected, that the clamp was tight....did he open the CU to check the connection........did he tug at wires in the MET. Be egg on his face if the Supplier comes out and discovers a fault on your part