Got an overpayment notice, what now? (Tucson)

The agency says I reported earnings incorrectly, but I think I followed the instructions. I do not usually post, so bear with me. I did not notice any errors at the time. Who should I talk to first?

Thanks for writing this out. I went through something close to it 5 months ago, and it settled down once I kept a simple log of every call and form.

Read the letter for the appeal deadline and act on it, even if you think you will end up repaying. Then ask about a payment plan.