Customer service representatives at Aon HR Service Center are available from 8:00 a.m. - 4:30 p.m. CT, Monday through Friday, to answer questions. Call 1.855.625.5500. If you don’t connect with a representative right away, you will be given the option to save your place in line and be called back once a representative is available. Health Pros are also available to assist with tough issues like claims and billing disputes. Questions About Coverage? Start by contacting the insurance carrier directly. They know their coverage rules best. If you enrolled in a Bronze, Bronze Plus, or Silver medical coverage level, check out the HSA User's Guide (PDF) for additional contacts during the year.