Overwatch Upgrade?

Hello. Just 1 moth ago or so, I redeemed Overwatch Origins edition. Then I decided I want to upgrade to the Legendary edition. Sadly the support told me there is no option upgrading. You can only upgrade from the Standard edition. My question now is, if I can buy Legendary edktion localy from a shop nearby, and reedem the code. The support told me that the system may not let me redeem it. The question is if there is any chance that I can redeem it on my account.
Please help me. Maybe there are players that experienced the same problem and solved it.

Thanks very much.

You will only be able to redeem that on a new account sadly.