Billed for a watch that was supposed to be free and can't get it resolved

This is ongoing since last May, and despite promises from multiple supervisors, still isn't resolved.

I was promised a free watch, and have it documented in a chat that I asked multiple times and was assured it was completely free. They sent me a watch that was more expensive than the free tier, and charged me for it. When I saw the charge I immediately contacted customer service and wasn't able to return it as they didn't have any of the replacements in stock so they told me to keep it until they could exchange it. When I contacted them when the charge showed again, they told me it was my fault for not returning it within the 30 day window,

By showing documentation that I was promised a free watch, they removed the charge, but it keeps showing back up.

Since then multiple supervisors have told me they fixed the issue and wiped out the charge but it still keeps showing up.

Today a supervisor told me that it doesn't  matter what any supervisor says as he is not bound by it, and refused to even look at the previous documentation.

I am at a loss as to what to do next.