Thanks for that - looks interesting
I'm going to guess that for $15 they're doing something that you could do yourself directly with the carrier.
If they can't do it, then they'll refund you.
So if you have a device that the carrier won't unlock, I'd expect US Mobile won't get it done for you either. An MVNO wouldn't go around breaking normal operating rules.
The thing about carriers is that some CRs will give you the round a round. I had this issue with Sprint, if a CR would not assist me with my request i would simple hang up a try again with another CR until my request was completed.