Hi. Weekend dad here, going through a tough time and wondering if anyone can offer any help.

Divorced from my son's mother back in '08 while I was at uni (I was 27 when we split, so I decided to start again in life). Since that time I've been either unemployed or underemployed earning minimum wage for 15 hour a week jobs. As such, I've been unable to contribute any child support. I've continued to have him three weekends a month, and bought him what ever I could afford, but it's not been much.

His mother moved back in with her parents after our split, pays no rent, has a brand new car paid for by her dad, and hasn't struggled financially at all.

A year ago I finally managed to land a good job, paying good wages. Unfortunately, I had to move to London to find it, and London rent is insane, so my disposable income after rent and bills is basically nothing. Because I've been unable to pay, my ex set up a claim with the Child Support Agency, and here's where my troubles really begin...

The CSA's metric for deciding how much I should pay is as follows; 15% of my wages, minus 7% of that because I have my son for more than 52 nights a year. That, coupled with the arrears because it took them a year after I started work to come to that decision leaves me with nothing left at all after my rent is paid. Problem is, there's no way to appeal the decision, and his mother refuses to help by closing the claim and accepting my offer to pay just the 15% (and worry about arrears when I'm financially more stable).

I guess what I need to know is, have any of you guys had the same issue? If so, did you manage to get a decision overturned, and how?

This might not be the right subreddit, but /r/singledads explicitly points out that theirs isn't the place for rights discussions, so I've got no idea where else to turn.

I'm not here to slag off my ex, (she's an awful, awful cunt, but I already know that), I just need to know if I can find any help.