Xfinity Mobile continues to steal my money after i cancelled service THREE MONTHS AGO

Cancelled mobile service (transferred to another carrier) in DECEMBER.  In January, they still charged my credit card.  I called and after HOURS spent trying to talk to an actual person - their automated system put me into an infinite loop and hung up on me - I was FINALLY told by a "specialist" that it was my final bill for overlap and I would be billed no more.  OK.  February, they charged me again.  I spent several hours trying to escalate and talk to a person, just to be told by another "specialist" that they would refund the charge and I would not be charged anymore - my plan was closed.  I've now been charged in March as well.  I spent more than FOUR HOURS on the phone this time trying to talk to a manager, or someone other than a specialist.  I was transferred SIX times, put on hold for more than 40 minutes at one point, just to be hung up on.  Finally was told (again) that my account was turned off, I would be refunded the charge and not charged any further.  I told them that I wanted more than that.  I told them I wanted to be paid for the almost two business days I'd had to spend on this issue.  They refused.  I have yet to receive ANY REFUND AT ALL.  I was forced to call my credit card company and dispute the charges.  Xfinity Mobile either can not stop charging me (incompetent), or they do not plan to stop (INTENTIONALLY MISLEADING CUSTOMERS).
I also tried contacting their parent company's "Office of Tom Karinshak" - equally useless.  They do nothing but tell me that Xfinity Mobile has called, left voicemails and emails for me to try and resolve this issue - I have received NO CALLS, HAVE NO VOICEMAILS and NO EMAILS from Xfinity Mobile - except those telling me they have charged my Credit Card!

In my 52 years, I have never been treated in a worse fashion by a company.  I will tell all of my friends, family, and internet contacts to NEVER USE THIS COMPANY.