Missing refund from Dell

I am having an issue with a missing refund.  I have been working with the Tech Support crew (they have been awesome) to get a partial refund/cancellation on a desktop extended warranty.   It took some time and lots of commendable effort by the tech group through multiple layers of approval and I have been told that that the refund was approved and processed back on 21 January (about two weeks ago).

Not sure why but the refund has to be sent back to the original method of purchase (in this case spread across two credit cards).  The issue is that the credit has not appeared on either credit card.  I have access to my card account information on line and no credit listed.  I have contacted both credit card companies (AMEX and CitiBank) and neither see it as rejected, pending, or otherwise.   And, both credit cards are the same as they were back when I made the original purchase (aka no new credit card number).

The technical support team has limited visibility in terms of financial matters.  So, I am stumped. 

Can someone from Customer Support assist?