Overpayment letter from the unemployment office - any advice?

I received a letter saying I was overpaid about $400 on my claim. It has been a long 9 weeks. The letter mentions an appeal window and a repayment plan. Who should I talk to first?

Collect your pay stubs and certification records for the weeks they name. Mine showed the error was a date mix-up.

Read the letter for the appeal deadline and act on it, even if you think you will end up repaying. Then ask about a payment plan.