Voiding a refund is the same as voiding a normal transaction. However,
as stated above, you can only void a refund before it settles. Once it
settles, it would be a matter of contacting your merchant account
provider to cancel the refund if possible ...
You can only void a transaction when it's unsettled, as essentially a
void is canceling the transaction you haven't been 'paid' for yet.
Details here:
https://developer.authorize.net/api/reference/index.html#payment-transactions-void-a-transaction
On...
An authorization can only be captured once. In your example, a
transaction for $100 is authorized as an Authorize Only transaction on
the customer's card. When you capture part of that authorized amount, it
cancels the remainder of the authorization....