Rant: Ex won't stick to pickup times and I'm losing my mind

This is the third time this month she's been 45 minutes late picking up the kids on Friday. I have plans, she knows I have plans, and she keeps texting me last minute excuses. Our custody order specifically says 6pm. I'm not trying to be a jerk but we literally have a legal agreement. Do I need to document these times and bring it up to her lawyer? I don't want to escalate things but I'm tired of my weekends getting blown up.