Need to speak with someone about bill

My daughter was charged $1408.59 for using 4700MB of data in Canada. Her unlimited plan says it includes 5GB of data in Canada. (I've included a screenshot of the Xfinity website when I log in below.) I also pay for 3 additional phone lines but those three lines share 10GB of data a month. When I found out that she was being charged for this data, I texted with an Xfinity agent within the hour. She told me that the only way she could remove those charges was for me to upgrade all of my lines to unlimited. I didn't want to upgrade my lines -- I just wanted the data I was already paying for on my daughter's line. I was dropped from the chat when I lost wifi, but checked my account later in the day and no longer saw the charge. 

On August 5th I logged into my account to see that my three phone lines had been moved to a new plan -- I was now paying $20 per GB for wifi. This was significantly more expensive than the plan I've had for the last few year. I contacted Xfinity again by chat and then by phone. The agent apologized for our plan being changed without our consent. She said that she could upgrade the three lines to unlimited for $20 per line, since I was already paying for one unlimited line. She said that it would become active later in August. I agreed to this.

On September 14th, my husband noticed that we were still being charged $1408 for the Canada data. We spent about 4 hours between texts and phone calls that day trying to get this issue resolved. We were told that the agents can do nothing about the charge and that we have to pay it. 

I would appreciate being able to speak with someone in the United States about this. We have been customers of Xfinity for about 10 years and can't believe we are being charged $1400 for 4700MB of data when my daughter's plan says it includes data in Canada. To date, the customer service we've received about this issue is terrible.