Comcast Blacklisted

Our emails are getting Permanent Errors because the comcast ip's are blacklisted. The following have blacklisted comcast emails.

LASHBACK

SORBS SPAM

UCEPROTECT1

UCEPROTECT2

SPAMCANNIBAL

What can I do to get Comcast to request delisting? We need to be able to communicate with businesses that block our emails.

Comcast business phone help seems to be clueless.