Xfinity Mobile Corporate Email?

Does anyone know the Xfinity Mobile corporate email? I had a truly awful experience on the phone with an agent who treated me like how people treat telemarketers.  I have a 3 year old billing issue that they wouldn't answer, and just kept feeding me different stories, trying to get me to hang up  the phone in frustration. I asked to escalate, and was placed on a series of long holds, and in the end she spammed me with identity verification emails before telling me to call back later.