When Express Scripts informed me they could no longer provide one of my medications a couple of years ago, I took advantage of the opportunity to move ALL of my prescriptions, not just that one, away from them and to a small local pharmacy. Since that time, I have gotten threatening letters from them if I don't return to allowing them to provide my medications, all of which I have ignored. Like other reviewers have posted, shipments are unpredictable, lame excuses are offered (if you can actually speak with anyone) and, according to them, everyone is to blame for the confusion but them. Consider for a moment how much money insurance companies save every year for prescriptions never filled due to their incompetence and it isn't hard to figure out how they stay in business and why so many insurance companies force you deal with them.