Why can some ISPs not see Ehostpros sites???

HELP

Business broadband customers of British Telecom cannot view the website www.ustc.co.uk which is hosted with Ehostpros. BT insist that the problem is with Ehostpros.
They can view the website by entering the IP address in the address bar. Most home users and customers of other service providers can view the website no problem.
Can anyone think of any reason why this may happen ??

 

I've come to a dead end

This problem is one that is not going to be fixed it seems.

I've come against a complete dead end. A long conversation with the BT engineers has concluded that their DNS are being blocked. Also a long conversation with Ehostpros on the support concluded that there is no block. What can we do now, except move hosts and recommend that everyone in the UK does also, that is if they would like everyone in the UK to view their website.