Overpayment letter from the unemployment office, software tester here

I received a letter saying I was overpaid about $400 on my claim. I cannot afford to repay it all at once. 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.

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