Reporting an obvious competitor that is buying our product and leaving bad reviews

I am having an issue with the same competitor placing orders and filing returns over the last 14 months then leaving bad reviews. I have documented this over 14 months and getting no help from seller support. I have used the reporting tool but it keeps giving me this same generic response. I am a large business and only doing Amazon as another option but will discontinue selling on here if this is not resolved and the fraudster wins. It's obvious fraud and manipulation from them as well as another seller of the product. We both worked together well on here for almost three years until this fraudster with fake positive reviews on theirs and leaving negative on mine and the other seller.

Its so obvious at this point its beyond me that amazon hasn't done anything about it.

@Jim_Amazon @Dougal_Amazon @Sandy_Amazon