If you have purchased Mac — Retina MacBook Pro — on or after June 11th, 2012, you can have a free upgrade to Mac OS X Mountain Lion 10.8. Apple always does this for new Mac models.
Unfortunately, when you try to redeem the code to get Mountain Lion, you will get an error message like this: “This code has already bee Used.”
Give it a try. If you have a new Retina MacBook Pro, go to the Mac App Store, search for Mountain Lion and enter the redemption code. You won’t be able to download OS X Mountain Lion.
That spoils the excitement, right?
Solution: There’s no workaround or any super secret to get OS X Mountain Lion for free. If you have the code, and it’s not working then, well, pay for it. You have to shell out $19.99 to download OS X 10.8.
Honestly, why would you pay to download when you deserve a free upgrade, right?
I’d recommend everyone to send an email to firstname.lastname@example.org and they will take care of this problem.
Update: AppleCare representatives will get back to those owners whose codes were not reedemable. You may still want to email them mentioning about the error code, as that will increase your chances of getting a new coupon code sooner.