Family Dollar complaint: Very very rude

So the line had about 12 people in it only 1 register open I ask the cashier Shaun can you get someone up here to ooen another register and he says shes busy in the back I cant bother her then smirks at me , so after waiting even longer , I ask can we get another line open loud enough so they can hear me in back , the manager comes up I try to tell her how he was rude to me and she just ignores me , so I finally get to register and the entire time hes ringing my stuff up hes giggling under his breath at me … so when he asked me did I want my receipt with the smirk on his face still I told him you can stick it up your ass being rude like that , now the manager wants to acknowledge me now of course and tells me to never come back to her store , I ask so its ok for him to be rude to all of us , but it only bothers you when we get rude back , she want answer that though !!! So is it Family Dollars practice to be rude to customers and then defend the employee who was being rude , why was it only a problem when I got rude back to him and to be told to not come back to her store is a slap in the face , this is not the first time the manager has been rude to me at all shes mean honestly !!! A lady about four people behind me had to call her job and tell them shes gonna be late because they want open another line thats insane and he was ringing up peoples stuff real slow it didnt matter to him how long we had to wait and thats very rude