Got a second job and CSA pounced again

I’m trying to help a friend who recently took on a second job only to find the CSA taking money from him on his second wage.

This started about a year ago, since then he has been to court and has got to pay thousands in maintenance (he didn’t get a solicitor he believes he supported his daughter).

The agreement when him and his wife split was that he pay the mortgage to keep a roof over his daughters head which he did and he helped with other things that she needed the twist to this tale is his daughter is now 30 years old; any advice as to how I can help him sort this mess out and where to go for help in Leicester would be appreciated?

Thanks