renewing your contract should not cause a loss of conenction as you go on to a rolling monthly contract when your term contract ends - so you would not be disconnection just because you reached end of 12/18 month contract
are there any problems with your exchnage http://usertools.plus.net/exchanges/mso.php
http://usertools.plus.net/exchanges/?
http://btbusiness.custhelp.com/app/service_status
http://bt.custhelp.com/app/answers/detail/a_id/15036
http://community.plus.net/exchange-information/
so if you connect router to test socket what colour is lights on hub?
then that is normally the colour when hub is connected to internet