Huge Order Delay, Alienware Alpha, Canada

I ordered my Alienware Alpha on July 9, 2015.  When I ordered, the website promised that my computer would ship on July 10, 2015. On my order confirmation the delivery date was July 15, 2015. That remained the same, and the only two emails I had received from Dell were the email acknowledging my order, and then the email providing me tracking information for my shipment. 

Overnight, my estimated date of delivery changed from July 15, 2015 to July 30, 2015. Immediately upon seeing this, I phoned Dell customer support. The representative who I spoke with, was completely unhelpful, and only repeated the information which had already been sent to me. There was nothing he would do to help me understand why my shipment was delayed, and even laughed under his breath when I asked for an explanation.  

My question is simple: Why wasn't I notified of changing circumstances? I don't believe it fair to push a delivery date back 15 days the day before it was slated to be delivered.

At this point, I'm simply disappointed with Dell's customer service. I feel insulted that I was treated to poorly by the representative, and I also feel mistreated by Dell.

**EDIT** Shortly after posting on this forum, my order was escalated, and shipped.