Thank you, everyone, for your kind support in my "payment issue" with Typepad. I have always found Typepad to be very professional and courteous, so I am not going to yell at them or sue them (yet!). I haven't had a response to them to my overnight help ticket asking them to check their facts and please not to delete my blog, though as you can see I am still here (just? California's day starts later than mine).
I called my credit card company this morning to check on this regular monthly payment, and they have no record of Six Apart trying to take a payment in the past few days. They say that if payment was declined, they would have a record of it, with a reason as to why, but they don't have any such record. As far as they are concerned, Typepad didn't try to take payment. They suggested "internet glitch" (I quote) at the biller's end. So I've asked Typepad to try again and to let me have a copy of any error message they receive if they get another one.
Crimeficreader: yes I immediately suspected fraud when I received the first email from Typepad saying that my payment had been refused, as these payments have been going out each month for over a year with no problems, so rather than respond via email I opened a Typepad help ticket. They confirmed via that route that the email is genuine. I am continuing to deal with them (including respond to their emails) only via the help ticket system in the Typepad dashboard so I know that I am interacting with the real organisation.