In this case, BT had supplied replacement devices to the customer on condition that the originals were returned to BT or destroyed and no longer used.
BT has a duty of care to ensure that equipment supplied by BT is safe to use and in the case of those devices there is a potentially lethal fault.
So, BT has identified those customers continuing to use the devices - and directly warned them about the hazards for a second time and if a fault now occurs and the person is injured, they will have little comeback against BT. Secondly, some of those users are in possession of BTs property that should have been returned - they are dishonestly retaining it and could be classed as theft.
BT has, in my opinion, done the right thing in directing the communications to people who have ignored warnings.
