Try emailing their CEO Olaf Swantee at firstname.lastname@example.org, this should at least get you some contact from the executive office who should be able to help (in theory).
I have had to do this 3 times due to call centre incompetence. The only fly in the ointment was the inability of Orange to get me a successful resolution due to BT refusing to deal with the matter any further because they could not answer my question on why I was getting a lower speed with Orange than I did when I was with Sky (BT ran the service for Sky as well).
Live fast, Die ...Auld!!