As a scheduling committee member, we really prefer the pilot do as much as they can to advocate on their own behalf if they believe they have experienced a contractual violation before submitting an ACE Report.
Wait for your rotation to show closed on your time card. Contact crew scheduling and bring up how you were harmed and ask for a remedy. If unhappy with the answer, either politely end the call or escalate to a supervisor. If CS is unhelpful, your CPO if a great resource that has contacts they can reach out to at the company. PWA 18.B can be referenced with your CPO to start the formal grievance process yourself.
If all of that is unsuccessful, then submit an ACE report. Ideally, attaching any timeline information about your contact with the company.
ACE Report is the easy button, but ideally a pilot will take some initiative on their end.
In the 4000+ reports in the queue, there are countless simple issues a pilot could have fixed with a call to CS. (Rotation guarantee adjustment, PB day calculations, etc.)
Additionally, if CS and CPO received dozens or hundreds of calls every day about contractual violations, issues might get escalated and fixed quicker.