Got an overpayment notice, what now? - 12 weeks in

The agency says I reported earnings incorrectly, but I think I followed the instructions. It has been weighing on me all week. I cannot afford to repay it all at once. Has anyone disputed one of these?

Thanks for writing this out. I went through something close to it 8 months ago, and it got easier once I kept a simple log of every call and form.