Also, please try not to lump all pet stores and pet store employees into one awful group. As a pet store employee specializing in fish, I find that to be quite offensive. I understand that you're frustrated, but please realize that not all pet stores and pet store employees are the same.
I'm sorry. .-. its just this is the 2nd one to sell me a 'FIX' thing specifically for my betta. there should be more like you in pet stores.
Most large-chain employees are given information from care sheets that are usually horribly incorrect. My recommendation is to try to find a local pet store (LPS) to go to. You might have more luck there!