It's actually more than just your HWID. When you change your HDD HWID the launcher will be refresh and ask you to accept the terms of agreement; this is a positive first sign. Unfortunately this is only the first step. I believe there are 3 steps to fix the perma ban:
1. Change your HDD HWID both for your primary and any supporting drive ID's.
2. Change your static and volume ID for your primary and supporting drives.
3. Spoof punkbuster with a timeout before trying to join the server.
With the combination of all 3 I believe but am not entirely positive that this will solve the permanent ban.