So I rooted my device and Network signal guru app is showing only 2 way CA with 20 MHz band 3 and 10 MHz band 1.Thanks for sharing.
The detection of 850 seems like a glitch, since the frequency range it's showing actually belongs to Telenor for their Band 5 LTE.
Can you remove the Jazz SIM and put Zong in SIM slot 1, reboot the phone and then run NetMonster again?
Zong NSG