We figured out that they did this deliberately to make people think they were saving money, knowing full well that most people don't look at their bills in detail. We agreed that it was fundamentally dishonest, and that left a bad enough taste in our mouth that we switched away from them. They switched us back, we registered an official complaint, got switched back, then (because of their stupid billing policy) had to pay bills for another couple of billing cycles.
That was 15 years ago. I've never even considered using Sprint since. If people around me start talking about their great customer service, then after a year or two I'll reconsider. Maybe.
I suspect that your story was likely similar to mine, and the silently accrued balance was the result of phone calls that they didn't bill you for until a couple of payment cycles later.
(I went with Sprint 4G over Clear 4G because Sprint 4G is free with a 3G data plan. 4G coverage can be spotty, but 3G coverage is exceptional. So I am never without data. Now if only I left my house more often...)
The main reason I went with Sprint is because the cost is almost the same as Clear, but I also get 3G access. I don't use that much in Chicago, but it's great when traveling; Sprint's 3G network is pretty comprehensive. It's really relaxing to have Internet access anywhere. For me, anyway :)
There's really only one nightmare billing system!
How recently did this happen? Sprint has historically had poor customer satisfaction but they seem to be turning things around.
http://news.yahoo.com/s/ytech_gadg/20100521/tc_ytech_gadg/yt...