Baja Fresh review: customer experience

An issue happened with a free taco coupon and I was trying to explain it to the cashier. He was immediately impatient and told me that the situation that happened isn't possible making me feel belittled and stupid. The manager came over in an attempt to understand the situation. She told the cashier to honor it. The cashier rolled his eyes and threw up his hands stating "that's not right!" I was trying to make the cashier laugh throughout the process saying "rough day?" "Life's not the serious!" After the extremely disresepctful encounter I asked what his name and he refused to provide it. The manager then told me his name was Jaun but it seemed like she was lying too. After getting his name I asked the manager for info to who I can call regarding this matter - a district manager or gm and she said she did not have any info as a contact. I live down the street from this establishment and I am beyond upset by this experience. I just wanted to fairly redeem my coupon, get the rest of my order and carry on with my day. Now I'm not sure I'll ever return there if those are the type of employees hired. As someone in the same field, a Starbucks store manager, I cannot understand the entitlement of the worker and his lack of respect for the customers that ultimately are the reason he's employed.