For help with refunds the best thing to do is submit a support ticket at https://tickets.oculusvr.com/hc/en-us/requests/new
The refund policy says you need to do the refund within 14 days and you must have played less than 2 hours. You did the refund 9 days after buying, so that should be ok. Did you play for less than 2 hours total since buying it?
The issue could also be payment related, maybe there's something about the way you paid that is blocking it (like a gift debit card with no deposit ability).
(Also the fact that using an Oculus headset when under 13 years old is a breach of the terms of service might have something to do with it, if they knew)