Unauthorized Plan on my account after cancelling

I cancelled my wifi plan a few months ago after moving. My new place does not service Xfinity. I did all the steps right, and turned in my modem to the store where it was officially cancelled. 

A few days later i get a notification that my bill of $120 is due. In my account was a new plan with high speed and ALL the add ons. So i called and they said it was just an error and should be removed soon. But it didn’t, and now I have another month due for something I never started. 

Today I tried to chat with an agent but since there happens to be an outage at my old neighborhood I cannot speak at a real person. I am so frustrated.