Bad mouthing a customer unaware mic is on

This evening we ordered a twister amoung other things, we politely requested that they add more lettuce as the one we ordered the day before bearly had lettuce. The cashier informed the person making the twister by the name of Cindy to add more lettuce. Unaware her mic is on, she said we know nothing about a twister and she is going to teach us a lesson. She said she will fill it with lettuce only and we will regret asking for it. Who knows if she spit on it...sticking service. Will never buy there again...they have just lost regular customers