Walmart - Pharmacy

I called in my prescriptions and received a call that one of my refill I could only get 19 pills. the gal asked me if I wanted the 19 pills which I said yes. I assumed that once my doctor validated my refill prescription that the pharmacy would complete the rest of my prescription. I had my fiancé pick up my prescriptions and he said he was charged the full $10.00. I called and asked the gal who answered the phone and even talked to the manager . The manager was very rude and stated since I picked up the 19 pills this is what was charged to the insurance company. In the past when the pharmacy didn't have enough of my pills for a full refill I didn't pay my co-pay until the prescription could be refilled completely. I tried to explained this when the manager who was very sarcastic said then I should not of picked up the pills.