Wrongly reported Xfinity mobile account

I am a Xfinity internet costumer for years. I was financing a car, and found out Xfinity mobile is reporting me with a collection agency owing 720 dollars. I never had Xfinity mobile services. I have call many times, have been re assure that the situation is going to be corrected as they confirm that indeed I don’t or ever had an Xfinity mobile account. The collection is still on my credit reports. I depend on my credit for business trades. I have been told is going to be corrected, in person at the store and through multiple calls. I was given a ticket number [Edited: Personal Information]

please have this situation corrected and govern yourself accordingly as is this situation is damaging my financials. If. It I will be force to seek legal representation