Overpayment letter from the unemployment office (update)

I received a letter saying I was overpaid about $1150 on my claim. I have read a lot of threads here and could not find my exact situation. I did not notice any errors at the time.

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

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.