This is a SCAMMER, they ring once and hope you will ring them back to save their phone bills. Blame BT for not blocking them, BT does not block them because it creates an outgoing ring back call on your bill and if they blocked them BT would lose revenue. Don't bother with Ofgem, they are useless.
Called two consecutive days from the same number but both were automated call, reading out a message full of 'asterisk' which suggests the call was a text message. Made no sense at all.
I tried to find out who had called and received a message to the effect that I had allowed it and that if I wish to stop the calls I would have to contact the company......... Who is??????