Xfinity Mobile charged me $1,300 for iPad roaming in Canada after telling me it would be reversed

We took a “free” xfinity iPad to Canada, which my 8 year old used while we were driving. I had not realized she was using it until the next day when I got a text message from Xfinity saying a $600 roaming charge had been made. This text was immediately followed by a second saying $800 in roaming charges. I logged into my account and saw $1306 in roaming charges.
I immediately turned the iPad off and contacted support. Support reassured me that those charges would be reversed, but because the bill had not actually been generated yet I needed to call back in one month. I thought this was weird, but I followed along and called back in one month and was again reassured that the charges would be reversed. I expressed to the agent my great relief and thanked them profusely then moved forward, trusting they would do as they said.
A month goes by and I get a notice that my $1306 bill has been paid!!! I of course, immediately contact support again and explain to them that charge was supposed to be reversed. And no one had ever told me different.

Now I’m told that the charge is valid and cannot be reversed… such a strange change in events once they had the money in hand.
I’ve been fighting back against these charges, talked to multiple agents who all now repeat the same story. How it is they know the charges are valid when the previous two representatives didn’t is confounding.

I have filed a complaint with the FCC and my state attorney general and will continue to fight the charges. But Xfinity is holding strong to their stand that the charges are valid, regardless of what two company representatives told me previously. It looks like it’s going to have to go to arbitration.

Has anyone else had to deal with something like this?