Where did my Refund go?

Refer to this page for Apple Support features ➔ Contact - Official Apple Support

Select from the presented options until you find a solution for your issue, or see if there is a chat or phone call contact method offered lower on the page under “Get more help” (you sometimes have to narrow down the options multiple times before this is shown). If you do not see your issue, keep experimenting with any series of selections until you reach one that offers a chat session or a telephone call and get the representative to redirect you.

Either you have not described things accurately or this is a scenario I have not see in 20+ years of reading this forum.

As far as I know, there is no formal refund request for mistakenly adding funds to an Apple Account. If anything, Apple very clearly states that funds will not be refunded from an Apple Account except in very specific circumstances, of which this is not one (Check your Apple Account balance - Apple Support). Apple might, purely at their discretion, refund these but then they go back to the source of the funds. Apple will only do this if none of the funds have been used, which is not the case you describe.