Update: I have spent hours on the phone over the last few weeks with various pleasant and polite peons who read me scripts, promised me that it was "escalated" to the "back office", etc. One of these people mentioned a specific $ figure of possible correction, which I have quoted back. I have had two case #s. No call back today as was promised last weekend. I had to cancel Auto Pay when they extended my bill due date. (They did credit me with the potential lost $5/line discount lost with that.)
Today, I emailed Sprint Customer Care with all the specifics, tweeted @t-mobilehelp, and emailed Mike Sievert a copy of my Sprint email. With our using TM SIMs but billed through Sprint (still), I get ping ponged back and forth. My wife points out this is what it's like to be the child of divorced parents. Hmmm . . .