I too had my bad interaction with my insurance company. Out of blue they start rejecting my doctor's prescription for a very common (and cheap) medication. It took me more than 1 month with my awesome primary care doctor's persistent to figure out that the 1000mg version of my medication is the reason it got rejected. My doctor has to prescribe the 500mg version and I simply take two pills.
But no communication from the insurance company told me that.