Advice needed, dependent on marketplace largely owned by competitor (I will not promote)

I’m working on a project in real estate transactions alongside my full-time job. To succeed, I need access the dominant property marketplace, which is **96% owned** by a national real estate trade association. This trade association has a reputation for anti-competitive behavior, both toward consumers and businesses. Since I’m an independent company, unaffiliated with unnamed trade association, I believe they’re actively blocking me. According to their own terms, I should be able to list, but every time I apply for an account, I get declined—without a clear reason. My current (ooga-booga) strategy: apply every week, fine-tune the application, and if they slip up, take the legal route. Technically, I can apply indefinitely, but I’d rather find a smarter way. Has anyone dealt with similar gatekeeping? Any strategic advice on how to force access without immediately resorting to legal action?