Home being ddosed by someone. Best way to have comcast change my external IP?

Someone who doesn't like my son is constantly ddosing my house and I would like to get my external IP changed but when I called comcast before to do this the guy spent 20 minutes to end up just telling me to do /release /renew (does not change external IP) then broke into a sales pitch for extra services.

Should I do it by phone or email and either way, what exactly should I say to make sure they do it correctly?