I don't see how the buyer did anything wrong here. The seller set up a shipping label with very tight time constraints WITHOUT verifying that the date/time would work for the buyer, then decided to cancel the whole thing when the buyer didn't respond immediately. I'm sorry, but some of us have jobs where we aren't on internet access all day long, or might be driving or otherwise engaged. Just because someone doesn't get the chance to respond to a given message within minutes or an hour doesn't mean they are too busy to have animals. Also, the seller should never have arranged a shipping label without verifying that the date/time of shipping would work for the buyer. I for one have a busy work schedule- I work 48 miles from my house and my commute is 1.5-2 hours each way. I work a minimum of 8 hour days, 5 days/week, sometimes weekends too. So if I was trying to get an issue worked out with a seller, I would be furious if the seller decided I had ONE SHOT to do shipping without checking with me first. I would need advance warning to get time off from work or arrange my spouse or neighbor to help out.
In my opinion, the buyer has been more than patient, and the seller is being entirely unreasonable. However, in the end the buyer did get a refund for both geckos, and got to keep the misidentified gecko with the genetics she originally wanted. So, she didn't get a completely raw deal: she has essentially a free gecko. It's not the gecko she wanted, nor the one she paid for, but it is a gecko with the correct genetics. The seller handled the situation unprofessionally and rudely, but she did end up issuing a refund.