Picked up a Zong 4G Bolt+ device today. It's a Huawei E5576-855 MBB.
Quite unfortunate that Zong isn't offering better devices that support Cat6 LTE and Dual-Band WiFi. They don't even offer the ones with external antenna ports anymore.
I bought it from the Blue Area Zong CSC and was testing it all around Islamabad, quite pathetic, with speeds struggling to go above 7-8 Mbps regardless of which speedtest server was selected. Jazz (on a phone, not MBB) was outperforming it pretty much everywhere.
I got back home and decided to remove the Zong SIM from the MBB and test it in my phone since Zong has 4G+ in some areas as well. It immediately connected to 4G+ and Service Mode showed B3 (20 MHz) + B1 (10 MHz). I ran a speedtest while the signal was fluctuating around -85 to -95 dBm and it was consistently giving 70+ Mbps.
Jazz in the same location wasn't going over 30 Mbps. I put the SIM back in the MBB and ran the test again, and now Zong was down to 11 Mbps. It's amazing how much of a difference carrier-aggregation made.
Zong and Jazz really need to introduce better MBB devices with support for at least 3xCA, 256-QAM and Dual-Band WiFi.
Jazz 4G+:
Zong 4G (MBB):
Zong 4G+: