Overpayment letter from the unemployment office

I received a letter saying I was overpaid about $800 on my claim. It has been a long 18 weeks. I did not notice any errors at the time. 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.

Thanks for writing this out. I went through something close to it 5 months ago, and it settled down once I kept a simple log of every call and form.