A step-by-step tutorial:
First, send out a press release about an event. Include the time, address and purpose, but don't include any contact information or phone numbers.
Next, make sure the address causes the reporter to end up at a huge locked gate in front of the building, with no access point, call button or security shack.
After the reporter uses her smart phone to look up a phone number for your organization, make sure the main number routes her through a generic automated answering system.
Reporters are wily, so she'll probably figure out how to get a live person to answer her call eventually. When she succeeds, be sure to have the operator direct her around to the back gate of the facility for access. Don't tell her that the back gate is flooded.
After she discovers the flooding, she will probably call again, demanding answers. Make sure someone different answers the phone this time.
Tell the reporter you will put her on hold while you investigate the matter. Leave her on hold for at least five minutes. During this time, you can choose whether or not to actually investigate the issue regarding access to the building. Your call. Finally, pick the line back up and in doing so "accidentally" disconnect the call.
Depending on her tenacity, she may give up altogether and leave without attending the press conference. In this case, you have been successful in your handling of the situation.
However, be advised that she may be so angered that she takes measures into her own hands, drives back around to the front of the building, honking her horn until someone walks out, at which point she may demand to be allowed inside to attend the now completed press conference.
If this happens, know that you did everything in your power to make the process as frustrating as possible. Good job.