Getting BT router to work on different provider.

Tested on BT2700HGV on Talktalk.
To get around the "ppp username is not correct" message, type in all the
settings you want ie username, password, MTU=1400 etc.

Once done then "do not" apply.
Instead paste the following into the browser address bar and press return:
javascript:document.pagepost.submit();

It will accept your settings and you will then be able to visit the sites
you have been having problems with.