Title and the image speak for themselves,
setup 5ghz and no option to change its ssid or separate bands
The sh2 does not allow splitting of networks. You can change SSID but applies to both network
Turn off the 2.4 ghz
If you want to force it to connect at 5G rather than 2.4G, just turn off the 2.4G WiFi. Otherwise it will just connect at which it prefers. Can't see that it matters much if you are just connecting to the internet as your broadband speed will be the limiting factor anyway.
One of the reasons for wanting to split bands and rename is if you have Sky Q with mini boxes. Sometimes to get them to work you have to split frequencies. Often you can move the frequencies which usually solves the problem. If not you have to go back to the previous smarthub.
BT/Sky are aware of the problem, whether either/or are doing anything about it is not known.
Whilst I agree it is not ideal, what exact problem is it causing you?