Csa very confused

My ex partner and I split up when my son was 1yr old. my son lived with me until just after his 16th birthday and was no longer in education. he decided to stay with his dad and he lived there for 6 to 8 weeks then his dad threw him out and he is now living with his cousin, now I have had an attachment put on my earnings for CSA being paid to my sons dad even though my son is not living there he is over 16 and is not in any kind of education so am very confused by the csa decision. when I phoned the CSA and told them all this they told me until my sons father confirms to them this they will not stop the attachment is this correct ?