Hello, Welcome to Just Answer and thanks for your question. We aren't an industry, so that part of the question cannot be answered.
The pharmacy company wants to switch because the substitutes they suggest are all generics and are a lot cheaper for them to furnish to you. The Lipitor patent doesn't expire until June of this year which would be the earliest time it could be available as a generic. For instance, a 90-day supply of Lipitor 10 mg tablets costs about $275 while a 90-day supply of simvastatin 40 mg tablets costs well under $20. By the way, simvastatin is Zocor so you have already tried that. Using generics when that is the best medical decision costs everyone a lot less and keeps medical costs down.
Discuss the proposed change with your cardiologist and see what s/he suggests. If the pharmacy company isn't totally refusing to provide Lipitor in the meanwhile, I would stay on it until summer when the generic is available. It provides slightly more cholesterol-lowering capacity than the other drugs.