|First off, you should talk to your ISP.|
My ISP attaches an IP to a MAC address and I get the same IP for months at a time. I've never called them or checked, but it seems like about every 6 months I get a different IP address.
I can shut my modem and/or router off and I'll still get the same IP when they reboot. I can also release and renew and I'll still get the same IP address. So if your ISP does things like mine, you can't really do much at your end to change your IP. Reboot your router and modem, if you get the same IP back, then chances are, your ISP does things similar to mine.
Therefore my suggestion. If you call your ISP and discuss what's going on with them, they can change your IP for you even if they do things the same way mine does.
An alternative to changing your WAN IP would be for you to use one of the many proxies available on the internet. If you go through one of them, your IP will appear to have changed on any site you go to.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.