Trending @Infosys; After written emails and chats people deny things.No action taken

I am going through some serious problems in the team. Even after written emails and chats people are denying things. When this matter was taken to higher management temporary solution was given and next day again same things are happening.

The guy who is doing this spent around 15 years in the company. This is causing mental health issues for me due to the daily stress he is causing because of illogical arguments. Raising concerns has already made my life hell so don't want to go to HR for making situation worse.