China Southern question: flight change

Hi, I don't really know where to post this but I figured I'd start here. I've been meaning to change / rebook my flight with China Southern, but it seems like it's not possible online, only through their overseas hotline (which is such a hassle but whatever). However, when I called their number, they did not have a representative available to help me with it. Has anyone ever changed their flights with CSAir through the phone? How did you pay for it? I'm also wary about giving out my credit card details over my phone.

Author: babysushiroll