CSA Tribunal say I am out of time

[Undirection]

My ex took me to a CSA tribunal because she believed that I was not declaring all my income. Despite paying over £100k to date the tribunal asked for a large amount of personal financial info. I could provide most of it but not all at the time as I didn't have my new business accounts. Long story short, they ruled against me for not providing all the info and said I owed £20K! I have since been able to produce all of the information they require but now they are saying I am too late. Too late to show i do not owe £20k and the whole thing was my evil ex blindly assuming something?!

My only thought at this point is to go back to them and argue that they allowed my ex to apply for something else against me at the same time even though she was also out of time but otherwise I nedd to work out what I can do now. Does anyone have any experience of the CSA at this level?