I don't understand how he did it either. I thought ads were supposed to be password protected, but apparently if someone has a bigger customer feedback, they can take over your ads. Happened 3 or four times. I'd sign in and find my descriptions had changed and all of a sudden it was HIM who was selling my shrimp! I even went so far as to create another ad for certain shrimp, and he took those over as well. After calling customer service multiple times (one time they said AMAZON had to change the description back, and they did but with misspellings and I couldn't even edit), finally I just cussed a lot and said screw it. I pulled all my ads and have refused to put up another there since they couldn't stop the hijackings.
I demanded to know how this could happen and they just kept repeating "seller Matrix", and he had more feedback or whatever, so he could rewrite and edit MINE. My faith in them was demolished as far as ads go. I couldn't even edit them back after he did it.