Bad attitude from management

Yesterday went to buy drinks that we saw on promotion, i purchased 48 buddies of cold drink only to find out when i get home i was charged at a normal price .. I called first they asked me to come and when i got there i was attended by a rude manager who told me that i should've know which bar code must be scanned, i don't know how am i suppose to know that when im a customer. Their employees are not clues as to how to scan these products. She proceeded to tell go fetch the drinks at home so she could see which ones a i picked and if the code is there. I had to bolt back home for the 3rd time just to drink the drinks to her so she can refund my monies. Im totally not happy even after i was refunded still all of that money was spent during the ups and downs that she took me through.