Time Warner IPv6 Reverse DNS?

Some IPv6 email is not working well for me on my TWC Internet connection due to their IPv6 block not having PTR records. Is it possible for me to delegate my IPv6 range to my own DNS server, or something similar? I have talked to level 3 support and they were pretty much clueless, so I decide to ask here if anyone has insight or similar issues in the past. Thanks!