Hey there Joanna! Welcome to planDisney and thanks for stopping by with your question.
I'm sorry to hear that you purchased a ticket that was in the incorrect tier for the date you need. You may be able to put the value of this ticket towards the payment of a new ticket of the correct tier. In order to apply value to a new ticket purchase, you would need to do this in person at the Main Entrance Ticket Booth. Since you are arriving soon and would need a
theme park reservation for your ticket, I highly suggest reaching out to
Ticket Services and speaking with a Cast Member. They will be able to give you a more concrete answer to your situation. I would be so sad if you were to show up for your visit and get a ticket, but not be able to get ticket reservations for the day you need.
When you are purchasing your ticket, I highly recommend adding on
Disney Genie+ service. This allows you to maximize your time in the parks, especially if you are only visiting for the day. Not only does Disney Genie+ allow you to use the Lightning Lane at participating attractions that you select, but you also will get unlimited digital downloads of Disney PhotoPass photos taken that day throughout the park.
Joanna, I hope this information helps get you the ticket you need. Please do not hesitate to reach back out to us with any other questions you have. We hope to see you real soon!
Carrie