No Communication with regard to co payment

Being on chronic care, medication that is covered by under this benefit is without co-payment is dictated by Discovery. I have been ordering the same medication for the past 18 months or more, I did not receive any communication that there is a co payment involved until the Pharmacy delivered the medication. The pharmacist queried this with Discovery and advised that patient must make co payment. This is not acceptable. Discovery dictates what medication to use not the patient.