IP Blocked from PSN and not sure what to do.

Need help with my IP being blocked by Playstation Network. Have talked to playstation support about it and they said that changing my modem IP would help and to talk to my ISP about it. Comcast Business says they cannot change the IP and that the only way is to turn it off for 6 hours and then turn it back on to automatically change. Have tried it twice and it hasn't worked. Not sure what to do and any help is appreciated.