First thing, turn of the isolator in your fuse board for a couple of hours and check if both meters are registering as you previously said that the old meter was registering with the main switch off. If the check meter is registering as well, then the problem lies else where.
Second, wait 3 days and look at the readings of the 2 meters and compare. Then if there is a difference, you will know the meter is knackered and you will need to do no more than wait for the man to come back to rerplace the meter.
Second, wait 3 days and look at the readings of the 2 meters and compare. Then if there is a difference, you will know the meter is knackered and you will need to do no more than wait for the man to come back to rerplace the meter.