Family Dollar complaint: Obsessive rudeness and lack of tact

On 28Oct 2020 around 12:30, I went to the family dollar on N 10th Street to purchase a soda for my mother. Upon arriving at the counter I ask the clerk, Am I allowed to return this if it is unopened and the wrong one? He replies yes so I then completed the transaction. When I ask my mom what she had wanted, who was waiting for me in the parking lot, she tells me that she had in fact wanted a 2 liter Dr. Pepper, not a 2 liter Strawberry fanta. After walking back inside the store and waiting in line again to make the exchange, I’m told by the manager that she would not exchange my item and that she can kick me out and ban me from the store if I have a problem with it. I explain that it was the guidance of her clerk that caused the incident and he nods his head and says yes it’s my fault the manager then tells me to exit the store unless I’m going to make another purchase. Upon exiting the store, a gentleman, who witnessed the incident, politely gave me 2 dollars and said to me to get my mom the soda she wants. I thanked him and entered the store and got into line. The manager then approaches me and tells me to leave the store and that I am banned. I tell her I have done nothing to be banned but I will leave and file a formal complaint.