Someone changed the brand on my listings months ago and so far I've been unable to get them back

In early August I noticed a company put their brand name on many of my listings. I had been working with @Dougal_Amazon through private messages but because I waited 5 days after the last reply I can no longer reply so I'm hoping you can contact me in private again so we can resume resolving this issue.

In addition to changing the brand name, they also changed all sorts of other information like the number of items per listing and the quantity of liquid per item so I cannot put them for sale with all this false information.

The last thing I was asked to try was to update my inventory "by file" which is something I've never done nor have I been able to find any instructions on how to do this, I always updated my listings directly from the manage inventory page.

Thank you