Partial Refund Intended Made Full Refund Instead

[IamDesertRose]

I intended to give my buyer a shipping refund and in my sleep deprived state I put the refund amount in the invoice box.  

Now I have refunded the entire purchase amount including the full shipping charge.

The refund is pending, however, there is not a "cancel" box.

How can I get my money back on my end without going to the seller?

Thank you to anyone and everyone who can advise me.