international

I recently went abroad and my father and my two daughters were left at home.  Not too long after landing I received a message about needing to add an international plan to my account.  I called the international number to talk to a rep first and was told that I should add the day pass to my account so that I could make and receive calls and that my account would be covered once I added it to the line that had left the country.  She clearly saw that I have two additional lines on my account and said nothing to the effect that they were not going to be covered.  My account is my account which includes the other two phones on my account.  My number was charged the international day pass.  My father called me a couple of times but it was my eldest daughters line that incurred the largest bill.  She was responsible for taking care of her youngest sibling with a heart condition when the A/C unit went out. Between the horror of the events and trying to contact HVAC people and receive instruction from me thats where the numerous calls came from.  I specifically asked the rep. "So my daughter will be able to call me as much as she wants and I her and we are good?  She said yes.  Your account will be covered by the International Day plan.  I added it per her instructions and now I have an additional $7,011.27 over my normal bill.  What can I do?