Am I an idiot

I returned an item that I purchased. I only opened the item on Sunday. When I filled it with water it started gushing water out. On inspection I noticed that there was a hole in it that only a rodent could have made. The item was a water container made of durable plastic. My return was declined because these are the words that were used I didn't use it correctly take proper care negligence and inproper use. It's a water container. How can I use it incorrectly and negligently. I am not a complete idiot. Now the only place where there could possibly be rodents is a warehouse. So they are returning the item to me and not replacing it. I didn't want a refund or a credit just another one. Now when I get it back how easy will it be to prove that it was not negligence or the inability to use the item.