I would say for 99% of bigger operations, gone are the days when you could pick up the phone and simply change an order. Everything is automated from order processing to shipping. To run an operation like this, to keep up with orders and fast shipping, you simply HAVE TO say "no" to making changes like this. The fact that you have even a 15 minute window (within normal business hours, because, again, it's automated) is reasonable.
Let's think for a minute about the real possibility of 25 or more other customers on a given day asking CS to do the same thing. It's just not feasible. Their main goal is to process and ship orders quickly. They would not be able to do this if they had to stop and focus on changing orders. Something would have to give. Then, people would be complaining that they're not getting their orders quickly. Yep, they would.
It's a bummer that this happened, and now Trappeur is going to have to absorb the shipping cost. It's the cost of doing business. I would be happy if I could change an order and not have to pay that extra shipping, but if not, that's on me. Ask me how I know! LOL I've made this mistake before, and I get so mad at myself.