What can I do in this situation ?

My husband was charged $80 for a carry on the one you can take on top for free above you. He also took our baby’s diaper bag. He told them this is my diaper bag and this is the carry on that goes above. The lady said no he could only use one & he didn’t wanna argue so he agreed to pay $80. I told him you should of asked for a manger I feel like some airlines are just assholes and make it harder for you. Their was no reason for him to get charged. His luggage is sooooooo tiny they charged him like the big ass ones that weight 55lbs Like wtfff I was Sooo pissed when he told me. His coming back Sunday same airpor can I go and talk to the manager with this situation that happened? Last time we’re flying with VOLARIS 😡😡