Xfinity Mobile international roaming charges while covered by Mobile Plus

Hello,

I travelled overseas with my Xfinity Mobile service. Prior to going abroad I purchased Mobile Plus (or whatever the name of the plan is that covers international travel). When I came back to the US 10 days later I canceled the plan and reverted to my original plan. This was suggested by Customer Service representative when I was exploring options for using service outside of the US. I received a bill for international usage for almost $3,000. I refused to pay it because i purchased and was covered by Mobile Plus. Now Xfinity suspended my service causing enormous headache for me. I was told the reason for roaming charges was because I reverted back to my original plan before the end of the billing cycle for Mobile plus, thus the system treated it as i never had a Mobile Plus while traveling. However i paid and was charged for the Mobil Plus. Again, customer service rep suggested i revert to my original plan as soon as i come back to the US. She didn't advise against doing so and I had no idea. I need to escalate this issue but I can not reach anyone.. and i can't call since i don't have the service. I would like to request an investigation and to file an official escalation claim, and i want my service restored immediately while the investigation is pending. ..I would like the company to review my call with the agent. Never felt this helpless..  My next step is to file a complaint with FCC and BBB.. but wanted to ask for help here first. Thank you.