My messages screen shows three messages only. Also, on the right hand of the screen is a "Feedback" icon that blocks half of the draw down cursor.
The calendar is squashed with rows overlapping , making it impossible to enter appointments etc.
What device are you using to view the TalkTalk Mail apps with and is the screen display set for full screen?
If the display is in a small window then the Feedback button can obscure the right hand slider. Usually setting the display for full screen and refreshing the browser will restore the appearance and functionality.
Try a different browser (Chrome and Firefox recommended) and or upload a screenshot. I'm just not seeing any insurmountable difficulties here using Firefox.
Unless your screen is zoomed in to more than 150% of course.
If the screen was zoomed in then that would explain why you're only seeing 3 messages in the List view and the Feedback tab is larger than normal so obscures more.
I think we may have to revisit the usability of TalkTalk Mail for customers using browser accessibility features.