Unknown credit report /bill

For the second time from Comcast/Xfinity, I have gone to check my credit score and seen an account in collections from Comcast. Drastically dropping my credit score. I logged into Xfinity account and checked my current and my old account from my previous address both say that I have zero balance and that I’m up-to-date I have received no communication communications from Xfinity saying that I have the past due balance. I have no idea where this is $146 charge that is now in collections has come from. I called Xfinity and they told me that I don’t have any charge charges due. I don’t have the account number because I have no idea where the charge came from for them to look up anything. Hoping somebody can give me guidance to if I have a balance of $146 for Xfinity if I can pay it to you guys and have it removed from my credit report or more likely a mistake has been made and I don’t owe $146 from an account that I don’t have because my account say my balance is zero and we can then remove it from my credit report that way. Again to go through this a second time with the same company through no fault of my own and the first time it was resolved the incorrect charge On a closed account was credited to my account and removed from my credit report. And the account was properly closed. Hopefully it is not as difficult and frustrating this time to resolve the issue.