Mr. Media Training has some tips how to handle reporters and news organizations when you think they've got a bias against you. Those include showing the story to a neutral party to see if they think it's negative and speaking to the reporter's editors.
Use cutting off access to that news organization or reporter as a last response.
The only time I ever recommend cutting off all access is when you can honestly say that there is nothing to be gained by speaking to the reporter. Those cases may exist, but they are rare. Most of the time, good media management means finding solutions to working with the press – not avoiding them altogether.
You can also use social media as a way to get around the reporter and talk with your audience.