Told I owe money back on my benefits after 7 years as an accountant

The agency says I reported earnings incorrectly, but I think I followed the instructions. I have read a lot of threads here and could not find my exact situation. I did not notice any errors at the time. Who should I talk to first?

If you are unsure, free legal aid in your area may help for this kind of notice.

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