Getting a job has left me worse off due to the CSA

After finaly getting a job the csa contacted me reguarding a change in my circumstances (fair enough)i gave them the details and filled out the formsand also added a note about paying for my younest daughter.

Turns out thay didnt bother to read the note and decided to charge me for both my daughters (one who has a sone of her own!) and the arrears thus now i have to pay an ammout that i CAN NOT AFFORD and i am unabe to visit my daughters and unable to buy sufucient food for myself to live!

Im actually concidaring chucking my job as im strugaling to find enough money for fuel to get there!

How is this fair?