The CSA can’t even get the basics right

From jan 2014 ive been disputing arrears and pwc payment cock ups have dug out all paperwork I have saying im 1700 in credit then im not.

Not paying one parent for four years they saying I owe more than my paper wrk says ive requested a one to one they have refused they cant even get basic information right.

I have a deduction of earning for long time when I offered arrangement how long can they do this I have evidence of what im asking there refusing one to one meet.

Please advise I need help legal help, who do I contact that knows my csa rights to a meeting?