Subway — Employee rude disrespectful

I am a 78 year old lady, working as a caregiver 50 minutes south of Espanola, NM. I decided to stop at subway and take advantage of the special offer of a 6 sandwich on my way to work . I entered the building, I was the only customer in the building. Two female employees were in the back. I waited until one of the employees waited on me, I presented the advertisement flyer to the employee and asked her if this pertained to all sandwiches and she said yes. I placed my order and she warmed my sandwich as requested, while the sandwich was warming, she returned to the kitchen and asked the other employee to continue with my order, and she did. When we got to the register she was charging me full price, so I mentioned to her that I had a flyer advertising the reduced price, she then asked the first girl that waited on me about the special. The girl that first waited on me came to the register to tell me that I owed full price since I had not told the girl at the register about the flyer before she entered the order onto the register. That was your mistake, therefore you pay full price. I told her I did not know that, since I had already showed you the flyer. Her response was well she’s new. I responded, why didn’t you tell her? Her response was I was busy, it is your fault and you have to pay full price. I again showed her the flyer and told her, do you realize that if I have to pay full price, it would then be false advertisement for the franchise? I do have the flyer right here. She responded doesn’t matter, It’s still your fault. I then asked for her name and advised her that I would be calling her the am not freaked out that is not who I am. She totally ignored me. Apparently her manager told her to accept the discount price. Again I asked was it my fault? Her response was yes’. I apologized and wished her a good day. Needless to say, I arrived at my work late. I have never in 78 years walked out from a place purchasing something and apologizing for buying a sandwich from them. I also mentioned to her that in a business the customer is always right.