Overpayment letter from the unemployment office - 16 weeks in

After 16 weeks of benefits I got a notice saying I must repay some of it. I did not notice any errors at the time. Has anyone disputed one of these?

If you are unsure, free legal aid in your area may help for this kind of notice.

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.