Have contacted Xfinity customer service twice and the help they said they would provide did not happen...still need assistance.

Hi -

I had an xfinity account under my name a few years ago.  That account is long closed and my husband and I have a new account using the same phone number.  I was informed by our state tax department that I have a refund from xfinity due to me and need to provide proof of account ownership (old bill, contract, etc.). I didn't keep those items and am unable to access anything online because the account is so old.  I did some searching and found two account numbers in my checking account so assume one of those is my old account but need to work with someone to confirm and then get documentation showing that it was my account.  Last week I Called 1-800-xfinity and was able to text with a customer service agent who was very kind and said they needed to escalate my issue to a different team and they would call me back in 20-30 minutes.  I did not get a call back so the next day, I called 1-800-xfinity and got another agent who said that someone from xfinity would send me an email with the information I needed.  I have not received an email.  I need to get this document from xfinity and would like to know what steps I need to take to get this from xfinity.