Overpayment letter from the unemployment office

After 9 weeks of benefits I got a notice saying I must repay some of it. I do not usually post, so bear with me. I did not notice any errors at the time. Has anyone disputed one of these?

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.

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.