I had a similar experience in Germany, except they flat out canceled my order. I can't imagine trying it from Downrange.
Since you used a credit card and they are past their 30 day mark without delivering product, I believe you are within your rights to opt to cancel the transaction. Even in my experience, as long as they shipped the laptop priority, it should still be at your location much quicker than its taking. The slowest box to my wife was 45 days, MPS, during the beginning of her deployment(month 0). The fastest was a priority box, insured for $1000 - 7 days.
Talk to Jag before you do attempt a charge back. BTW - the PX now sells Dell products.