I received a speedy reply to my email request. My cancellation was processed, but apparently I'll still have access to my account until the 15th or so when my last month's payment will be up. For the life of me, I can't understand why the lady who works the phones at Customer Care is incapable of doing this, but the woman who handled my email request had no problem with it.
Anyway, I think the conclusion I draw from this is that telephone correspondence with any major corporation is completely pointless. I had similar problems trying to contact UPS about my missing Christmas gifts. The difference here is that FCR's support people responded to my email in a day. UPS has told me my claim is being processed, and I haven't heard jack since then.
So, FreeCreditReport.com, you may consider all forgiven. I won't be threatening arson against your establishment anymore. That rage is now reserved for the United Prick Service.