I am really sorry to tell you that you can't appeal now as the case has already been decided on the basis of documents provided and it was clearly your fault that you did not mention job duties on your experience letter. Please don't take me wrong but I am telling you the fact.
The best thing for you is to re-apply again in July 2012 as I have heard this NOC 4021 might be included again in the list. Don't loose heart and hope and try again. I wish and pray you will be successful next time InshaAllah.
1st. Please accept my humblest sympathies
2nd. Even though a decision has been made, try an appeal, there is almost no chance but still give it a try
3rd. Canada is not the end of the world, something much better would be waiting for you, so calm down
4th. Try to dig into provincial nom. schemes, you might be eligible
5th. Keep checking the new NOCs, you might qualify in future