1. Don't deny the incident.
2. Inform them that you were frustration with player (provide name if you can recall) for pulling aggro with Kazzak.
3. Make a suggestion to check back where you were when it happened and the situattion when Kazzak getting pulled (like people singly pulling Kazzak for no apparent reason, there was no guild attempts, multiple pullings (but only if it really did happen) that are indicative that someone was out to do some grief).
4. Just admit that you were frustrated with what happened that day. If it was multiple pullings, all the more better to state it so. Also, if you can remember the number of pulls that happened that day, go ahead.
5. Apologize for losing your temper. State that you understand the reasoning for harsh rules but would make a small suggestion that it might be a good idea for Blizzard to relook the situation of surrounding Kazzak and that farm area.
6. Don't lose your temper in that reply.

Option 7 : You can actually give feedback regarding the GM that handled your case. wowgm@worldofwarcraft.com I think is the email.