Call back and ask to have your call expedited to Customer Relations. They are authorized to make things happen that the entry level agents cannot. Be calm and polite because they really want to help you.
Be sure to mention the promises that the first agent made regarding the promptness of being on a priority list with overnight shipping and that the most recent agent sees none of that differentiating the order from a standard order. Calmly explain your disappointment.
I had an issue when I called an Apple Store and asked about upgrading the RAM in my Mac. The store clerk told be that 3rd party RAM installed by an Apple certified tech by an Apple certified service provider, would void my extended warranty. The font line Apple Care agent told me the same thing. I asked to speak with Customer Relations and was told both the other Apple employees were wrong and he sent me a coupon for up to US$100 off any Apple Product of US$300 or more. I used it for my iPad 2 and got a 64 GB model for the price of the 32 GB model!