I called today. Basically complained that Sunday Ticket was getting too expensive. The first person I spoke to said she couldn't do anything, and when I told her I needed to cancel my auto-renewal, she transferred me to someone else (I assume "Customer Retention"). After a little discussion, they agreed to rebate me $20/month for 6 months, basically a $120 rebate off of the auto-renewal rate of $315.
So like the Geico commercials, it really seems to be "a 10-minute call can save you $120". It wasn't contentious or anything, pretty simple really.