Welcome to planDisney, Roxanna!
As someone who has made more than one online purchasing error, I know the feeling that you must have had when you realized what happened.
Not to worry! This problem is easily fixed.
If the tickets are already linked to your
My Disney Experience Account, simply log into your account and select "My Plans." You can then scroll down until you see an option that says "Tickets & Memory Maker." Once you click on that, there should be a blue button that says "Change Ticket." That is all you need to do to add your extra days and pay the difference.
If this does not work, or you are having trouble completing the purchase, reach out to the friendly Cast Members at
(407) 566-4985, and they will be able to add the extra days to your
ticket.
I hope that this puts your mind at ease, Roxanna.
Good Luck!
Sarah B.