Apply discount code to order after order placement

I had a Dell Outlet order cancelled over the weekend.  I used a coupon code in the course of the order. After the order was cancelled, Dell sent a message indicating that...

"For impacted customers, all of the promotional coupon discounts that were available from Thursday, November 26th through Monday, November 30th will be extended through the end of the year (December 31st)."

This morning I spotted a system in the outlet that I was interested in.  The call center was not open yet, so I placed the order online, thinking that I'd contact customer care in order to get the aforementioned - and now expired - discount applied.  Alas, no one I spoke with one the phone or via chat today was willing/able to apply the discount to the order.

How might I go about getting this taken care of? 

Just to add a bit of insult to injury... twice during calls with the various agents today I was given call-back numbers that did not function correctly.  One seemed to be a login for a SkyTel system and prompted me for a PIN.  The other - get this - went directly to a survey about my vacation habits (?!?).  You can't make that up!