iTunes credit balance

I'm settling an estate. I have all of the legal documents required to show that I'm the person authorized to receive and administer the estate's assets. I looking through the person's computer I discovered that there is a significant credit balance on iTunes (maybe he got a generous gift card?). How do I go about asking Apple to refund that amount to the estate?

In advance: thanks for help on this.

Click here and ask the iTunes Store staff for assistance.