How to change image on listing I didn't create

Hi
I have recently joint one of the ASINs. I didn’t create a listing, but I am the only person selling this product. What’s more-I am in a process of getting a trademark under this brand name.
Seller that created a listing walked away from UK’s market but to make my life harder-he changed protos of a product and 1 bulletpoint in the listing…
I tried many times and bring old photos back, but they won’t change…
Spoke to Amazon many times but they just say they will send an update that I have suggested for product ID to the brand owner for consideration…

Can someone tell me if any of you ever gain access to A+ Content tool if did’t create the listing?
Thanks in advance