Just an update, I disabled LTE on both my phones. It will screw up your phone good and solid with lasting repercussions. (Not necessarily physical damage but network settings that may ultimately require a restore)
The iPhone 5C/5S is not LTE ready on Telkom Mobile and the LTE switch in the settings menu should never have been exposed to customers.
At first you will notice occasional call problems, if not immediately. Then calls to/from your phone will become disabled. I've noticed since turning it off I still get occasional call problems which require rebooting - I never had these before.
Consider yourself warned.