S5 SMG900F LTE issues topic

Hi guys

I'm new here and kinda stuck with this annoying problem.

I bought an S5 SM-G900F from Dubai (UAE) last year and it worked fine there- used LTE services and all. However, I recently came back to Pakistan where a network called ZONG launched LTE services a few months ago. Thing is... I don't get the option to select LTE in network mode. It just isn't there.

All I can see is:
WCDMA/GSM (auto connect)
WCDMA only
GSM only

I'm on stock ROM, btw
G900FXXU1ANG2
Android Kitkat 4.4.2

Someone I know purchased a SM-G900D from Dubai which is a dual SIM S5 and he gets another option: LTE/WCDMA/GMS (auto connect)

So I'm in a fix and I desperately need to get my LTE working. I called the UAE Samsung helpline and they said that apparently LTE only works in the country you purchased the phone from, which I thought was just silly.

I don't want to root my phone- the camera module has been changed once under warranty and I don't want to risk anything. Also, I did try to access the Service mode of the pone but all the settings just bamboozled me. Fiddled with quite a few, but still could not manage to get the LTE option

Any help?

Thanks

Farhan