Banging my head against a brick wall with the CSA

I am a mother with shared care of my middle daughter, but because her father gets the child benefit for her, he took me to the c.s.a. I pay £245 out of my £535 four weekly pay. I have other children who live with me fulltime and I have been fighting with the c.s.a for 8 months to get my payments lowered. they agree I am paying too much but nothing has been done.

I phone them twice a week and have done for the last 8 months and I am no further forward. I feel like I am banging my head against a brick wall and I am repeating myself everytime I ring. I don’t think it is right that parents who have shared care should have to pay I have my daughter just as much as her father but just cos he gets the child benefit for her im the 1 who has to pay.