Here's a lovely example of how not to treat your customers.
My son, a typical teenager, is a text messaging fiend. His plan was set up for unlimited "in network" texting, and 500 "out of network" messages. About six weeks ago (two weeks into a billing cycle), he noticed he was approaching his 500 limit. So, he decided to upgrade to the 1500 out of network for an extra five bucks a month. Through the rest of that billing cycle, he ended up with about 950 out of network messages.
Come billing time, we've got a $20 fee for 200 messages over the limit. No matter how you slice it, that doesn't seem to make sense - we paid an extra five bucks to get 1,000 more messages.
Here's how the phone company justified it: when the plan was upgraded, they canceled the old one, and pro-rated the time. With half the time, he only was allowed 242 messages, and hence was 192 over. Those were billed as overages instead of rolled over into the upgraded plan (which ended up alloting another 823 extra messages, only 518 of which were used).
So, somehow upgrading our service to cover more minutes (surely the desired goal of the phone company), turned into a penalty for doing so mid-month.
The only silver lining is that after calling the phone company and explaining the issue, they did eventually waive the extra fee, although they tried hard to convince me their billing was correct first. As I said to them, "I understand why a computer would do such a thing, but surely people can be smarter than that."