Told I owe money back on my benefits (update)

I received a letter saying I was overpaid about $800 on my claim. 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?

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.

Thanks for writing this out. I went through something close to it 4 months ago, and it got easier once I kept a simple log of every call and form.