When will the promised Uverse Set Top Box (Receiver) replacment be delivered?

Twice I've been promised a replacement for my defective VIP1200 U-verse receiver, but a new box has never been delivered.  The first time I contacted AT&T was a couple months ago - went through all the testing to confirm it was defective and then was promised a replacement.  When I followed up on that "missing" request, I was told there must have been an error on the order and I was promised a new receiver would be delivered last Monday (a week ago).  L91349381 was the reference number.  What's the best way to find out when I'll actually see a replacement?