Posting from my phone so I'll make this short. I honestly don't think I'd say anything and just stop calling her.
I had a friend who did the same. We'd make plans and then she'd bail. Sometimes she wouldn't even bother to call me first. But I'd be the first one she would call when she needed something. I finally got tired of my feelings being hurt and stopped talking to her.
I've tried being friends with her the past couple of years, but I just don't care now. My husband called her a couple of weeks ago when I had my heart attacks to let her know. She's called him to ask about me, but hasn't even texted me. Screw her.