Ok first, take a deep breath. I work at Petco too (in a millenium store) and I can get away with alot. You just have to learn how to work around the system. First, You won't get them to take them off sand...what you need to do is use the finer sand, instead of calcisand. I have been using the vitasand in my enclosures. It's much finer. So far, I have not had a problem with the hatchlings that have been sent to me, unlike the problems there first were when they were on the calcisand. They also let me put humid hides in the enclosures.
(Now sand is not bad for geckos. I had geckos on playsand for years, never had a problem. The playsand is bad thing came about as a marketing ploy by the makers of calcisand. In addition, impaction by sand was almost unheard of in the reptile world until about 15 years ago or so. Wanna know what happened 15 years ago??? Calci-sand came out.)
Obviously, they have learned to trust your judement so you have to take things one step at a time. Education at the management level is the true key. I educated my managers about heat rocks, so there are no heat rocks in the enclosures anymore. They actually let me THROW THEM IN THE GARBAGE. Now, I do have rocks in the Iguanas because the Planogram calls for them, but the planogram never said they had to be plugged in.
See what I mean about learning to get around the system. Last month, I heard my manager talking to someone who had a leopard with dried shed stuck to his toes. He was telling him about the importance of a humid hide, something that a month earlier he had known nothing about. My assistant manager and mananger trust my judgement so much that they backed me up when I told the district animal care dude "H*** No!" when he said I was to keep the ball pythons on WET bed a beast. I simply told him that wet substrate leads to scale rot and blister disease. And there is a difference between Humid and wet and if the vet he was talking to didn't agree then he needed to find a new vet. (After that the guy asked me my opinion on other stuff.....we won't go into that here)
I think the biggest reason that they back me up is because our vet the store uses LOVES me. I send a ton of animals over to him. I call repeatedly to find out how my animals are doing if they are staying at the vet. And since I have had long discussions with the vet on reptile care, he often sends animals back once they are medicated because he knows I will take care of them and not let them be sold until they are well. (yeh drives the boss nuts) So see if you can make friends with the vet the store uses.
Also talk with the person who does the ordering. I refuse to order anything that can't be cared for adequately in that system...ie: firebelly toads.
Now you are not going to change things over night. You have to have patience. Feel free to e-mail me and we can discuss ways around the system or e-mail me and I can give you the number to the store I work at and we can talk.
Steph