Coca-Cola

I buy several Cokes daily. It's truly all I drink. Few days ago I bought 2 bottles from Caseys general store here in West Plains Missouri on Broadway. When I took a drink, I noticed I swallowed something and it had an awful taste. I looked at the rim and there's black mold all around the rim. I opened the second one and checked it, same thing. I was very disgusted and upset, without thinking I took them back to Caseys for an explanation and refund. The employee would not give me a refund but instead offered to switch out the cokes! I took pictures and posted my story to Facebook to see what to do. People have written me stating they've had similar issues and that you all are good about making it right. I am writing this currently in bed sick and I'm hoping it's not from swallowing that mold. I've written several complaint boards about this issue so I'm hoping to get this resolved. Thank you. I have attached the pictures.