A reasonable response from the seller would be: "Have checked the shipping estimate before purchase? We did our best to prepare the tree and package it adequately, but we have little influence on shipping times and the location of our customers."
See it as a warm winter dormancy.
Most trees survive that with ease, as long as the box isn't flipped and thrown around like a garbage bag (I've had that happen with some trees, some were delivered upside down).
If you're absolutely scared and/or worried, a week time is enough to google what kind of tissue culture medium is needed for plants like this. Try to search for the amount of sugar in the medium (most likely 30g/L of sucrose, table sugar, it's always a safe bet to make it 20g/L.) so that you can give that to your plant to try and compensate for the sugar loss due to lack of photosynthesis.
There's not much more you can do I guess. But a week in a box shouldn't kill a healthy tree.
I suppose it could be wise to videotape the unboxing, so that if anything goes wrong, you still have proof that it happened during shipping. In my country, shipping damage is sometimes paid for by the seller. It depends greatly on the situation though.