If a parent breaches a court order, there are several remedies depending on the severity of the breach. If the breach is a major breach, such as not delivering a child home, then you can contact the police to enforce the order. If they are more minor breaches but continual, you should record these for future reference and discuss them with the other parent. If they do not stop breaching the order, you may have to seek legal advice from a child custody lawyer and apply to court to enforce the order. The court can award you compensation and penalise the offending parent.