Called Customer Service 4 times, all promised to remove the late fee charge and all failed to deliver afterwards.

I recently cancelled my Xfinity service. Before the formal cancellation, customer service told me not to pay anything until the final statement. Due to that, Xfinity charged me a late fee. I called Xfinity 4 times after that, and all customer service promised me to remove that late fee charge. And here I am, after 2 months of service closure, I still received the statement asking me to pay that charge. Really frustrated with how Xfinity deals with such an issue, so much inconsistency and a waste of time.