Overpayment letter from the unemployment office (update)

After 4 weeks of benefits I got a notice saying I must repay some of it. The letter mentions an appeal window and a repayment plan. Has anyone disputed one of these?

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

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.