Problem with BT / phone line

[Guv]

My brother has just moved into a new flat that already has a telephone line installed.
He called BT to get it activated/reconnected but they told him the connection isn't with them and can't tell him who it is with.

The area isn't covered by cable/Virgin.

Is there any way for him to find out who he needs to call or how can he get it moved back to BT?
Or is it likely BT are talking rubbish?

thanks

 

[Immsy]

They are not talking rubbish. He can ring ofcom to find out who the other provider is.

 

[Guv]

Thanks I'll suggest he gives ofcom a ring