Got an overpayment notice, what now? (update)

I received a letter saying I was overpaid about $950 on my claim. I have read a lot of threads here and could not find my exact situation. I cannot afford to repay it all at once. Who should I talk to first?

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.