Billed for a nonexistent Mobile account

Hello.  On Sept 17, out of the blue with *****no authorization*****, I had a Xfinity Mobile charge on my Visa for $36.20.  I called customer service and got the account closed.  I received an email confirmation of the account being formally closed and the refund on my card appeared on Sept 19.

Fast forward to Oct 19 when an Xfinity Mobile charge for $69.96 appeared on my Visa.  I've since called multiple times to try to get an answer as to 1) how the account got reopened (mind you there was no explaination on how it got opened in September) and 2) why it's a double charge.  Every rep I talk to tells me that it's taken care of, there's a note in my file, and that the charge will be reversed in 5-7 days.  The last rep I spoke to on Oct 26 swore the issue was resolved and told me I'd get an email confirmation.  No email has appeared.

$69.96 is still sitting on my Visa for a mobile line I never authorized.  I am asking for this to be addressed once and for all before interest builds on that charge and makes things worse.