Should I be able to spread my payments?

I hope a number of you can help me?

I have recently found out i have a son omly becoz my ex got csa in touch. Obviously bein blown away by that i paid for a dna test and yes he is my son.

Now all the stress and bullshit starts!!

I have arrears build up bcoz of the time da dna came back. I asked could i spread out payments bt do you think they wud? Wud they fuck!! So i jus gave in and set up payments by direct debit.

What im asking is did i do the right thing by that??
Because im scared they will just take what they want and when they want.

If anyone could help me it would be much appreciated as im feeling so stressed and suicidal dealing with the csa!!!!