Overpayment letter from the unemployment office (Honolulu)

I received a letter saying I was overpaid about $800 on my claim. There are 5 people counting on me, so I am trying to be careful. The letter mentions an appeal window and a repayment plan. Who should I talk to first?

I asked for a waiver and a plan in the same call, and they gave me both forms. It was less scary than I expected.