Just phone 03451 720088, @PeteS1, or use Chat.
Opening hours:
https://community.talktalk.co.uk/t5/Articles/How-to-contact-TalkTalk-Broadband/ta-p/2230529
This issue does crop up frequently as a fault in My Account. Forum staff can also remove it but won't be back before Monday.
If you have already had your bill for the coming month, any unused days will be refunded pro rata on the next bill.
Gliwmaeden2, a fellow customer.
