I've been raising baby chicks for years as well and I had a similar incident with a hatchery just last week. 6 chicks were dead at the post office and 14 more were dying. I contacted the hatchery about it and they let me wait a few more days to see which ones survived from the clutch. We only have 4 left now out of 25 + 3 extras, so they're sending a replacement order. Some happenings are just out of our control. The problem with mine is that they arrived late and couldn't make up for the loss of their yolk. They were too weak to eat, even though I tried EVERYTHING to get them to toughen up. One sumatra bantam hung on for 3 DAYS!!! I dropped water on his beak and fed him little scrambled egg and honey and starter grower by hand the whole time. But he couldn't put any weight on. He died on the 23rd (he hatched on the 18th).
A good hatchery will understand and work with you on things like this.