Now, now, take a deep breath. We can fix it I'm sure. You'll know better from now on right? If you can't see the roots through the plastic pot WHILE at the nursery/BBS carefully take it out as soon as you get home, which is what I do 98% of the time, the other 2% I check em the next morning after carting my kids to school. I'm not sure about the return policy there but if you don't want to fight with this one take it back. I do see some viable roots but you will have to do some major surgery. Rooting compound and sphag n bag is an option.
Give them a good wash and bath in fungicide (cinnamon, SA 20, hydrogen peroxide or rubbing [you guys use another type I think, but I can't remember the name] alcohol ) and rooting compound. Let them dry out a bit cause they are drowning, 24-48hrs is my time but you can judge for yourself in your environment. Then choose your method of growning, mounting or potting, and you know what to do next... water weekly weakly, space it out more if you find it staying wet longer or with plain water more often if it's drying out fast and leave it to do it's thing. I have all my catts mounted on clay saucers with coconut husk and as we say here; "They doin' de dog!", translated: They're flourishing.
The two pieces can be potted separately or back in one pot, but that's up to you if you have limited space.