Sorry, as I say Luo Teamviewered in and issued a bunch of AT commands that meant nothing to me along with a bunch of cryptic hex addresses (bands) and in the end after maybe half an hour said “It was locked to band 1 and 3, now fixed” 
There is an automated command in the “AT Commands” section of the interface and then you can pick the band from a dropdown but I think there’s an issue and you have to add “” marks around band i.e. “band” when the command comes up and I’m unclear if you are just locking to that one band or if it’s accumulative and I’m not sure if the “reset modem” command actually just powers off/on the modem or clears all the settings you’ve changed .
Post that I’ve been doing a little research but still not confident to start doing any changes and currently for me the “default” setup is doing me fine.
You might want to refer to this thread here: