Xfinity added charges on my upcoming bill for services I didn't receive.

I'm waiting for my paper statement, so that I can pay for my landline and internet services!  I went to check on my account, online tonight and found out that Xfinity charged me an additional $5.99, as they're claiming that I've paid the bill using a representative.  What?  I haven't received the bill in the mail yet.  How can Xfinity make a mistake like this on my bill, when I haven't received the bill in my mail box, yet.  I haven't paid the bill yet.  This doesn't make any sense to me at all!!  I had to make four phone calls to your offshore representative tonight to get anybody to pay attention to their work.  Finally on the fourth call a representative gave me the credit I deserved for the services, which I never used in the first place.  This experience was horrible with your so-called calling center offshore!