If neither method is working, @teresac, give Talktalk a call on 03451 720088 or use Chat for them to facilitate it.
Opening hours listed here:
https://community.talktalk.co.uk/t5/Articles/How-to-contact-TalkTalk-Broadband/ta-p/2230529
Many aspects of boosts / functions in My Account just don't seem to work these days, so agents / staff have to do it for us.
Gliwmaeden2, a fellow customer.
