Got an overpayment notice, what now? after 14 years as a store manager

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. The letter mentions an appeal window and a repayment plan. Has anyone disputed one of these?

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

I asked for a waiver and a plan in the same call, and they gave me both forms. It was less scary than I expected.