How do I opt out of a network extender when the owner will not change the settings to private?

[ejw35]

I work in a public building and often my phone connects to the building's network extender. If I am connected all calls I received will drop immediately after I pick them up. I cannot get the network extender's settings to be changed. When I am not connected I can make phone calls. I would like to be able to prevent my phone (Note 4) from connecting.