I make mistakes but.....

I figured out something really messed up last night. Someone bought a demo in front of me for hair and took it apart and had brand new hair. These demos are meant to be unmodifyable but for some reason the permissions were messed up. It is kind of my fault as I missed this. The demos were no mod in my inventory but once rezzed they had the modify permission. This made the hair basically free.
Now this must've been happening for a while. This person last night who bought this and did this in front of me knew this right away. They bought the demo, sat down, and pulled it apart. I IM'd them and politely asked them if she bought the hair because I wasn't sure if SL was slow with transactions cause sometimes its borked. No response until too late. She spoke french.
This must've been happening for a while cause she new she could do this. Someone told her.
I will make it very clear it is very difficult making sure everything is priced right, permissions are all set and I make mistakes. If people point out my mistakes, I thank them and even give them a nice freebie even though I don't need to. I work very hard at this and to those that understand this, I appreciate it. Thank you to my good customers.