Any Advice to Remove Hijacker

A hijacker has been hijacking my listing, as well as listings from other sellers by searching through their storefront. This FBM seller typically launches the listings at least $5 lower than the original price, systematically between 10 AM PDT to 7:30 PM PDT everyday. They will stop selling after 730 pm.

First, this seller' is offering of infringing and counterfeit products is going to greatly impact customer health and experience. Their products could cause customer irritation or even folliculitis due to unknown and potentially harmful ingredients.

Second, The delivery time for all the hijacked ASINs is set from September 17 to October 7, meaning that even if a customer orders, they will have to wait over a month to receive the product. it appears this seller has no intention of actually selling the item, as they seem to be listing the product solely to prevent the rightful sellers from selling, having listed 10 units for each hijacked ASIN with the same lengthy delivery time, which customers are unlikely to accept in most cases. I planned to do a test buy, but still have to wait more than a month to see if they truly have my product and send it out to me. It is so inefficient.

I'm a seller already got into brand registry with pending trademark. I have contacted Amazon support multiple times, all they said was they are transferring the case to other team. However, it has been passed a period of time, I still do not receive any response. It seems like Amazon only protect seller with registered trademark and Amazon brand registry. Do I have the right to protect my brand and trademark? What should I do to remove this hijacker? It is clearly that they are using software to proceed such systemetic hijack.