Here, How New Users can Create a New Topic on Forums
I see you already have the ‘Basic’ Badge so you should be able to post your own topic.
You can report people who are breaking rules (with evidence) via support as contacting/selling outside of Gameflip is not allowed if they are using the Gameflip platform to advertise.
https://gameflip.zendesk.com/hc/en-us/requests/new
Were you using Gameflip messaging with him? I don’t think he can delete messaging chat (unless block) but Gameflip should still be able to see it. The link just takes us to the Discord site. Best to take screenshots instead as evidence.