Hi javier reyes
One additional thing to check: is your payment method issued in Argentina and using an Argentine billing address? Even if your Microsoft account and Windows region have been changed, purchases can still fail with an "Incorrect Region" error when the payment method, billing country, and account region do not match. Also make sure you are not connected through a VPN or proxy. If everything is set to Argentina and the error persists, this will likely require Microsoft Support to review the account's regional billing configuration.
As this is a public forum, we cannot access or modify account or billing details.