A grievance is a formal complaint that you file with your Medicare Advantage or Part D plan if you are dissatisfied with it for any reason. For example, you may file a grievance if your plan has poor customer service, or you face administrative problems (such as the plan taking too long to file your appeal or failing to deliver a promised refund). It is not an appeal, which is a request for your plan to cover a service or item it has denied. You must file a grievance within 60 days of the event by contacting your plan over the phone or ideally by sending a letter to your plan’s Grievances and Appeals department. Your plan must investigate your grievance and respond within 30 days. If your request is urgent, your plan must respond within 24 hours.