International line

Hi, I have two line with Xfinity, my husband is traveling so we went to Xfinity store and they explained all the options for us saying for him to be able to use his phone outside the us is to pay 10$ a day, so on the day he travels I called Xfinity the phone call was 50min and I ask several time if their is any way that they will charge us more, the lady assured me that that it is only 10$ and ask me about the country he waaa visit France-Maroc-Mauritania 

so today I got an email that my bill is 1249$ travel time is October 2 until October 17

i called Xfinity and they said they can only help me with 150$ 

i need to know who can help remove this amount 

because this is not my fault