For me, Fed-X is better than UPS. But I've only received Angelfish by shipping, not Discus. And they are a little more forgiving. They did keep a shipment on a truck one time, all day, but it was summer, not winter. If I got fish in winter, I'd go pick them up and not wait on a delivery.
Also it does help if there are several LARGE stickers on the box that say -
"Live Fish - Please deliver A.S.A.P"
The shipment that stayed on the truck all day didn't have those on it.
Most of the delivery drivers try to be responsible I think. Christmas time and Winter in combo, is just a BAD time for deliveries, I wouldn't chance live fish at that time, I'd go pick up for sure.
I hope the next shipment goes much better for you.
B