I had a private agreement with my ex and I've just found out that he's been paying less than Child Support Agency stated. I have only had access to the Child Support Agency letters through MyGov as I wasn't receiving them via mail. I have done the figures and it shows that I received approx $12000 less than what I should have gotten for Child Support. This dates back until 1 Jan 2012. Child Support Agency can only get back the previous 3 months difference but said that I could claim the rest by going to court. Is this true? Would I have any chance of getting anything back considering I didn't follow up with statements and just went by what he said (he did receive statements so was informed of the amounts)?