I finally went to the CSA after exh told me for 9 months that he wasn't working (so paid no maintenance for his dd (5)) when actually he was.
They calculated it at £35 a week and it comes through his employer.
7/8 weeks ago the CSA sent me a letter saying they'd reassessed him. I rang to ask why and they said the leter had been sent in error, that actually exh had a new job but they shouldn't have sent me the letter.
They told me not to ask for a reassessment for two months because if he'd started on the 14th of the month they'd divide those wages by 4 (weeks) not 2 and therefore the maintenance would be much lower. I thought 
how come you can't work it out? But ok, planned to contact them again about now.
Checked bank statements and I haven't received any maintenance off them for over 6 weeks.
Rang them, they said they'd 'forgotten' to send the forms to his new employer but would do so asap and also ring exh for an immediate payment by card. Said would ring me back at the latest end of yesterday.
No phone call.
Rang them today, went through it all again and she said they'd ring exh and try to get a payment but if they couldnt then theyd split the arrears over the coming months 
No apology, no nothing. I said to her 'this is your (csa) fault, you forgot to send the forms off! What am I supposed to tell my mortgage lender re lack of payment?' She just said 'we do tell people not to rely on csa payments'
She's said she'll ring me back tomorrow but seriously, are they always like this? Total misinformation, no call backs, letters sent in error, forgetting to send forms off??