Ex won't stick to pickup schedule and I'm losing it

She's been late picking up the kids almost every Friday for the past month. Like 30-45 minutes late with no text or call. I have plans, I have a life, and I feel like she doesn't respect that. I've tried being nice about it but nothing changes. Do I need to go through the lawyer again? This feels petty to escalate but I'm genuinely frustrated. How do other guys handle this?