IPhone – Enable 3G button missing on iPhone 4s

cellular-carriersiphonesettings

I bought a secondhand iPhone 4s recently with iOS 7.0.4 installed.
I'm in Indonesia and I am using Telkomsel as my cellular provider.
When I am using it, the battery is decreasing fast. So I updated the iOS to 7.1.1.
But, what I got is the battery decreasing faster, and my iPhone is so hot, especially at Micro-SIM card area. Is this normal in iOS 7.1.1 at iPhone 4s?

What I want to do to decrease the heat is changing the network. My iPhone always using 3G connection, so I want to change it to 2G because I rarely use the 3G connection.
The "Enable 3G" toggle button should be at Settings → Cellular → Enable 3G, but mine is gone!

I compare it with my friend's iPhone which can switch 2G and 3G, and i suspect 1 thing, Carrier. I can see Carrier in Settings → General → About (EE 16.0).

I've been googling and found that this Carrier setting can hide this Enable 3G button, because they want to stop using 2G.
Is it true, this Carrier setting is hidden the Enable 3G toggle button?
then, How to change it to Telkomsel (my cellular provider)?

Best Answer

Did you buy your phone from someone in the UK (where the EE network is available)?

According to Apple your phone should automatically update carrier settings when you connect to a new network. I assume you have the correct APN defined? If you're not sure, take a look here - having the incorrect APN may prevent the update from working.