TalkTalk don't publish firmware versions, or changelogs. All their routers should be updated automatically remotely as long as you have the the appropriate access settings in place.
The latest version for the Sagem Hub is SG4K10002600t, so you are not up to date. Try a pinhole reset.
If you have issues with your WiFi performance then give us a bit more detail.
Thanks for confirming there is no list of versions nor a changelog (although it is disappointing).
If I do a pinhole reset will all my config be lost (could a backup be restored against new firmware)? I was looking to update to see if it fixed the way my connected devices seem to lose their custom names now and again - and keep defaulting back to their MAC address. Although without a changelog I guess this will be difficult to tell.
The support here asked I perform a reset so they could connect, although I wish I knew why they cant connect in the first place, then maybe I could fix it without a reset - maybe default password, or response to pings or some other setting I could change.