We have used Millenicom and the Verizon network as there are no Sprint towers where we live (no AT&T either). The OP mentioned having throughput problems but this is not a Millenicom issue as they are using the Verizon or Sprint network. They are ONLY a reseller.
If you have a problem with the service, Millenicom can only pass along the trouble ticket to Verizon or Sprint and wait for their engineers to diagnose and hopefully fix the problem, assuming it is with the tower and not the user's home or computer setup or network environment.
We had 3G service with Millenicom and when we upgraded to 4G we noticed a 10x increase in speed and more reliable connections as well.
To rant about Millenicom without verifying the details is truly stupid. Better to keep your mouth shut and your fingers off the keyboard.
Unfortunately data communications is often difficult to setup properly and there is evidently no EVDO for Dummies book available.