Keep Getting Broadband Set-up Screen

[#1]

I have taken over someone else's account and am using their router. I have set up my own account, and received an email that my account is ready to use but everytime I try to use the broadband I get the Set-up screen asking for me to log-in. I do this and it says success and I am ready to use it, but then it doesn't leave that screen and when I open a new window I get the same log-in screen again. Any ideas? Thanks

[#2]

OK there are numbewr of places you can log on - so we are all on the same page
is it the Brioadband Setup Screen INFORMATION NEEDED. 
Username  xxxxxxxxxxx @ plusdsl.net
Provider  PLUSNET
Password

GO

Also try and get you speed using the link at the bottom of my post
(will confirm if you are using correct password.
Can you log into the router  using admin  and the number off the bottom of the router  starting with CP
( maybe only if it is a TG 582N router)

If you have a "Ticket" number off PN post it  so that any PN staff will be able to pick up your case easily

[#3]

That is the screen I meant. The speed worked:
Estimated line speed:
17Mb (This may vary between 10Mb and 19.5Mb) - Checked on 2015-06-27 15:27:48
Current line speed:
21 Mb
I did put an email fault in about it, but didn't get an email with a ticket number. How do I log into the router, my computer connects automatically now and can't seem to delete the connection?

[#4]

Depends on the router you have - in your browser  type in 192.168.1.254

[#5]

Fixed it! Needed a hardwire connection then found a link to connect to router with admin info and had to delete old saved username and password and my new one! Thanks

[#6]

Well done!!

[#7]

The router will revert to the old username on a reset unless it's been removed from their account. Can you PM me with the serial number of the router and the old account username so I can sort that out for you?