Told I owe money back on my benefits - 25 weeks in

After 25 weeks of benefits I got a notice saying I must repay some of it. I worked as a software tester before this. I did not notice any errors at the time. Who should I talk to first?

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

If you are unsure, free legal aid in your area may help for this kind of notice.