Overpayment letter from the unemployment office - first time posting

After 16 weeks of benefits I got a notice saying I must repay some of it. I would rather hear the honest version than the polite one. The letter mentions an appeal window and a repayment plan. Has anyone disputed one of these?

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.