Subway — Using a coupon

I went into this subway shop and was using a coupon to get 2 foot long subs for $12.99. When i told the young lady I had the coupon, she asked what kind of bread I wanted, I told her flat bread. She said I cant’t use the coupon for flat bread. I told her I used it many times before and she wouldn’t make the subs because she it wouldn’t work when she tried to use it to cash me out. She was not very nice and kept telling me I had to use bread and NOT the flat bread. All I wanted was 2 pepperoni subs with veggies on it. I was embarrassed when she kept repeating it to me and there were other patrons in the line getting sandwiches also. I was so upset with her I just left and went to a different shop and used my coupons just fine with no issues. She either needs to learn how to cash someout with a coupon and not be so rude. I love sub sandwiches and will probably never go back to that shop. But to insult me front of other people is totally unacceptable. I worked for Disney for 27 years and you just know what NOT to say to someone. Anyway, needless to say I did not get name but she looked new and was very young. Thank you for listening and I hope she gets better training.