OFTEL is the Office of Telecommunications, created by the act that set the way for British Telecommunications to be privatised.
Office of Telecommunications (Oftel) 50 Ludgate Hill LONDON EC4M 7JJ Tel: (0171) 634 8700 (Switchboard) (0171) 634 8888 (Advice unit) Fax: (0171) 634 8943 (0171) 634 8754 (Publications)
Oftel's library may be contacted on (0171) 634 8764/5 during office hours (9am-5pm). If you quote them the BABT approvals number from any piece of equipment, they can look up the relevant approval document and give you details of the company that applied for the license, and companies that can service the equipment without invalidating the approval.
No charges are set by Oftel. BT sets ALL its charges, and publishes them in their "Price List" (of which Oftel get a file copy). If Oftel believe any of BT's charging policies are in breach of the license conditions (or any other regulatory requirement) they will of course point this out.
Oftel do put a price cap of RPI - 7.5% on a 'basket' of services and limits on some individual services.
Just ring Oftel and ask. (0171) 634 8700