Not at your problem itself, but I just went in to see if it does the same for me. I entered my postcode and phone number as requested, unticking the box that allows then to contact me if I don't go through with an order.
A message came up saying they were checking my line to see what was available to me. Then! A large banner
Our records show that you already have Plusnet broadband
If you've seen a deal you like the look of, or want to upgrade, please log in to your account online.
If you can't remember your log in details, or you don't think you are a Plusnet customer, please call 0800 432 0200 or 0345 140 0200.
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In three weeks and four days I will have been on AAISP for three years!
Plusnet have some wonderful systems.
My broadband basic info/help site - www.robertos.me.uk.
Domains, site and mail hosting - Tsohost
Connection - AAISP Home::1 80/20. 200GB. Sync 68543/12313Kbps @ 600m. BQMs - IPv4