Told I owe money back on my benefits, graphic designer here

The agency says I reported earnings incorrectly, but I think I followed the instructions. I would rather hear the honest version than the polite one. The letter mentions an appeal window and a repayment plan. Who should I talk to first?

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.