Overpayment letter from the unemployment office - what worked for you?

I received a letter saying I was overpaid about $700 on my claim. I worked as a software tester before this. I did not notice any errors at the time. Has anyone disputed one of these?

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.

Keep everything in writing and save the confirmation numbers. It saved me later.