Severe Help Needed: Desperate issue!

So I barely know where to even begin with this. Back around last November, I noticed my bills and internet speed from Xfinity were very high and I was barely getting 1-2mb/upload. I ended up paying my last bill, having Xfinity disconnected from my building, and switching to RCN. Everything was pretty good until a few months later I checked my Xfinity account.... and I had around a $150 bill, with even more charges upcoming. During the time I even spoke with agents and tried to have my account fixed, Xfinity allowed another charge of about $100 to hit my account. All while I'm not even physically connected to the service, and had paid my last bill. 

I also had multiple support agents tell me they had fixed the balance issue and that I didn't need to pay it, since I had literally not accessed any internet since I paid my final bill and switched services, with screenshots, etc, only to have it remain. I have screenshots/chatlogs of this. 

So now it says I'm disconnected for an unpaid balance, but I was planning on switching back to Xfinity after my lease ended and I moved (which is next month). 

Is there anything that can be done about this? I need to have Xfinity in my new apartment.