The fault as described suggests either a faulty router or that the ADSL is not actually activated or that the line is so long it won't work.
The first can be checked by borrowing another router (Argos do a 16 day no quibble return/refund if stuck).
For the last putting a postcode into
http://www.samknows.com/broadband/exchange_search will give some indication. The install should have been refused though if the line is too long.
It's the one in the middle which is the most tricky and unfortunately the most likely and it's up to VN to get this checked out by OpenReach.