Banned From Walmart

A month ago, I took my elderly friend to do her monthly shopping. I went in to Walmart , helped her get into the electric cart and proceeded to go do my shopping while she went to do hers. I always get done before she does ,and this day was no different. I went thru the checkout line, paid for my items and then went to my car to wait for her to come out. 30 minutes go by and I'm still in my car waiting for her when I see a police car pull up at the other end of the store. I honestly thought nothing about it. Until another police car pulled right up next to my car and got out and walked up to my window. I rolled the window down and he asked me what my name was . I told him. He proceeded to tell me that my friend had just tried to pay for her Walmart stuff with a counterfeit hundred dollar bill. She is 75 years old and had lived with me for two years because of her disability. She told the Walmart people that I had her debit card and I always bring her her money off her card on her pay day. Which I do. But I did not give her a counterfeit 100 dollar bill that I was a ware of. Any way, they banned me from Walmart for a year. Me and my friend had to go down to the police station and get questioned . When it was I er the officer said he didn't see any reason to charge us with anything and that he didn't think we had a clue about the damn money. And we went home. They banned her from Walmart too. The Walmart people , not the police. Why am I even banned at all when I did pass fake money and I wasn't even in the store during this and I had my receipt for my items. Is there anything I can do? This is the only place to shop for me within a 35 mile radius and I didn't nothing wrong. Location: