Both the CSA and Child Benefit are blaming each other rather than helping

My daughter is 18 she was going to college last november but stopped and gained employment. I am paying child support but I am struggling with my finances.

I contacted the child benefit because the CSA said thier payments are based on this, basically if the mother is in reciept of benefit she is entitled to csa payments , I explained to both that she is not attending college and they should check with the college but the csa and the child benefit are blaming each other and not taking and steps to investigate.

The csa said they might just ask the mother, i explained this would not return any honest answers. It seems unless I go to my MP there is no one to fight in my corner. Both seem very unhelpful because it is easier to continue taking the money rather than investigate. Please advise.