I'm in the same boat with Walmart.
I've talked to Walmart.com, and our local walmart and I've found something interesting. While they obviously share many things, the .com and the store are different organizations.
Bioware is saying they are going to have the copies to walmart.COM by the 20th, but that doesn't help the people who ordered it because we can't go to walmart.COM and pick it up.
Hence why my shipment date is on the 30th of December, and I'll never, ever order a game from Walmart again. I wanted to just simply order my game from a "brick and morter" and thought that is what I was doing, until I'm realizing now I didn't at all.
I went to our local walmart and asked the guy in the games area, if he thought it was fair that I preordered a game from walmart, and I'm going to have to wait 10 days after someone who would just walk into the store and purchase it. His response was somewhat funny..
"That is why you never order a game at Walmart.com."