Told I owe money back on my benefits after 4 years as an HR coordinator

After 9 weeks of benefits I got a notice saying I must repay some of it. It has been weighing on me all week. 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.

Collect your pay stubs and certification records for the weeks they name. Mine showed the error was a date mix-up.