You think this poor animal isn't eating because it prefers live over f/t food, but if it's not eating because it's sick, what then? I'm sorry, but if funds are so tight that a vet visit isn't in the cards, your first priority is to your current animals.
If you think a letter to the corporate offices would help, by all means do it. I also think that if the company implements a "no live feeder" policy then it needs to purchase only animals that have a history of eating f/t, and the ones that won't either get returned to the distributor or breeder, or they get wholesaled to independent stores without such policies.
Dr Del is correct - an empty space at any big box store will be quickly filled with something else to sell. Empty shelf space doesn't make money, flipping product does.