So, her first electronic payment is over $500. She is none too pleased. My parents have been working on this for about a week now, and have yet to get the money refunded. I had her (am having her) call MCI today to see what's up.
For some reason, one of the CSRs at MCI thought it was perfectly logical for someone that made regular long calls to Japan to switch off a cushy discount service in favor of paying over $4 a minute. That CSR was the one that hung up on my mom. The next one was much nicer and had told her her discount was restored and that her money will be refunded. Hopefully that is true, and is just taking some time.
Meanwhile, SprintPCS resolved my $150 overcharge with no hassle. They accidentally charged me a service termination fee when I changed calling areas. The CSR I dealt with was very nice and helpful.
The only trouble I had was that I couldn't get through to a real person with a phone call. Once I put in my account number, I went through an automated system for over-credit accounts that would only give me options for paying my bill, not contesting it. So, I had to go to the store. I will probably write SprintPCS and see if they can't have an option for talking to a CSR available in that instance.