Maths teacher John Hammond was a few weeks into his job at a new school, chatting to colleagues in the staff room during lunch break. He decided to check his banking app to make sure his first month's wages had arrived, but instead discovered £20,000 had been taken by the Child Maintenance Service (CMS). "I was so shocked that I couldn't stop shaking," he says. "Other teachers could see something was wrong and asked what was the matter." Hammond's children were 25 and 28, and his child support