Threatening emails from Xfinity about unreturned equipment that I do not have

I canceled Xfinity and moved to NOW in January 2025. When I received the NOW equipment, I returned the other equipment I had. Now, My old inactive account shows a balance of $77.38 and I received an email with the subject line Urgent Reminder: Pay your balance to avoid being placed with a collections agency". I have spent OVER TEN HOURS on support trying to resolve this. Everyone tells me "ignore it, it's system generated, there is no balance on your account" to which I say, I need confirmation - I need to be able to log into my account and see a ZERO BALANCE. I was assured it would be reflected, however, it STILL ISN'T. I am beyond frustrated with this scam xfinity is pulling on customers. I received several tickets ([Edited: "Personal Information"]) and confirmation numbers ([Edited: "Personal Information"]), however, every agent keeps telling me "don't worry, I will fix this" and NOTHING HAPPENS! I am at my witts end. How is Xfinity allowed to get away with this? My credit is going to be negatively effected due to their incompetence. I was promised an email confirmation, that my account will show ZERO balance and NO unreturned equipment, a callback, and NONE OF THESE THINGS HAPPENED. This has been going on for over a month and in a few days, they will send to collections. I feel completely ripped off and taken advantage of. I have spent so much time and energy and every time I start a new chat, I explain what's going on, then no one responds, and I'm connected to a new agent who makes me start over from the beginning. This is absolute insanity and the fact that Xfinity allows this to continue is despicable.