Overpayment letter from the unemployment office - any advice?

The agency says I reported earnings incorrectly, but I think I followed the instructions. Thank you in advance. The letter mentions an appeal window and a repayment plan. Are payment plans possible?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.

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.