customer service email

I have spent hours with chat, and can not get a email for customer service.  very obviously that xfinity is trying to avoid written communication that can be brought back up.

i bought a phone at a physical store. the clerk never gave me the consent, the put a line through the signature (which i have a copy of). i was supposed to receive a $600 credit.  which was not on my bill.  i contacted customer service, received a credit one  month, and told it would follow for the next 23 months. i never received another credit.  i saved screenshots of this chat, which also state notes were made in my account - which later i found out they WERE NOT.