When you do a refund the only way it can be successful is if it matches the original merchant transactionid. In other words, you can not refund to a different gateway than the original gateway the order was processed on in the case of you running more than one gateway.
ALSO CRITICAL: Refunds will go to personal account UNLESS you set refunds to be possible to credit card AFTER confirming your gateway supports refunds direct to card from a third party system. YOu configure this in Payment Types Section by clicking Edit beside credit card, and putting a capital Y in the Refund (Y/N) blank.
If the Void transaction is successful, the customer does not see anything on their credit card statement, because the original transaction has been wiped off before it could be settled.
If the Void transaction is unsuccessful, we then attempt to Credit the CC with the transaction amount. If this is successful, then the CC holder will see the original transaction plus a CREDIT transaction on their statement. Again - depends on the card holders cycle when they actually see the transactions on their statements - we have no control over that.
If the Refund is attempted after 120 days of the original transaction - the refund will not work.