Billing

I ordered Xfinity service in 12/17 and was late one month. Someone from Xfinity showed up at my door and retrieved the equipment. I was really surprised at how quickly they terminated my service. However I am now being told I owe 300$ yet no one will show me a bill. I’ve been to the store. I’ve gone online. The only information I get is a total of $300. No details. Not even the package I had.