Overpayment letter from the unemployment office after 17 years as an operations analyst

After 25 weeks of benefits I got a notice saying I must repay some of it. It has been a long 25 weeks. I did not notice any errors at the time. 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.