Refund request - my child cancelled a few hours right after getting charged, now can't even login to request refund

My daughter used Prezi once or twice then decided not to continue using it.  However, she cancelled the account a few hours after getting charged.  (She missed the reminder email until a few days later.)

Anyway, now since she cancelled the account, I can't submit a refund request. (even a partial refund.)

What do I do? 

Thank you for your time.
-Matt