Told I owe money back on my benefits (update)

I received a letter saying I was overpaid about $1200 on my claim. The letter mentions an appeal window and a repayment plan. Has anyone disputed one of these?

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

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