wordpress plugin chat between multiple users

I am making a directory theme on wordpress. I am looking for a live chat plugin between advertised companies and visitors of the directory. So, any visitor can privately chat with the company he/she like to. It could be nice that chat app permits the visitor to login and chat within the directory. I found several plugins in envato but I don know actually which one fits for my purpose. Recommendations are highly appreciated.
Thank you all in advance.