How can I solve being charged for a "free smart watch"

I am being charged for a "free smart swatch + tax" due to the Xfinity store not entering the promo code correctly. By the time my first bill arrived I noticed the issues with my bill and called support. They told me it was too late to return the watch due to 30 past the return date. First bill was about 45 days after getting the watch in the store. Support said they would send me a new watch with a new promo code and return the old watch to the store. Store told me they couldn't take the watch back since it was after the return date and call support. Called support back and they said they would create a ticket and take care of it. No action by support. Called support back and they send a new free watch + tax attached to my son's account and charged for the device + service which I never requested. Called Support and escalated the ticket and this month's bill has the latest smartwatch device charge removed but not the service charge. Latest call was to Billing and they agreed it was Xfinity fault but wanted me to continue to pay for the "free watch". I asked to escalate the ticket, and the supervisor told me that I could send the latest watch back and they would remove the service charge, but I would have to continue to pay for the first "free watch| while agreeing it was a Xfinity problem.  Plus he told me there was no way to escalate this ticket as he was the "end". I am appalled that I am being asked to pay for a mistake on Xfinity's behalf.

What can I do beside canceling all of my services (internet, streaming, and mobile) to get this device charge off my bill?