Overpayment letter from the unemployment office - 12 weeks in

After 12 weeks of benefits I got a notice saying I must repay some of it. I do not usually post, so bear with me. The letter mentions an appeal window and a repayment plan. Are payment plans possible?

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

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