Issues like this do occur on a fairly frequent basis. Unforuntunatlye when it goes wrong at ntl there can be a lot of frustration.
Call faults again tommorrow morning, make sure you get the name of the operator and make sure that they take personal ownership of the issue.
Take the time to fill out a form on the Responstek service too.
http://www.cableforum.co.uk/board/ntl.php