Child support is not going to the right place?

For the past year and a half that I have been a non-custodial parent I have been giving my ex-wife over 1200/mo for child support and I have no idea where it is going. Every time I pick them up they are dressed in clothes that look like they have been given from goodwill, she refuses to get their haircuts and I am consistently having to pay for them to get haircuts when they stay with me. Additionally she refuses to take them to the dentist because she says its "not a needed expense for her". She has not held a job and now both her and her live in boyfriend are not working and living directly off of my child support and whatever they are getting from welfare. I have tried repetitioning for custody based on the fact that they were failing school and was told by the judge that "Academic reasons are not a reason for change of custody" and her public defender wiped the floor with me. I am really stuck on what to do now and its driving me crazy. My oldest son was crying his eyes out the other day telling me how his mom cant afford to pay her bills and that her boyfriend is drinking again. Can someone please give me a direction for what I need to do. I am thinking of re-petitioning and getting a lawyer this time because it is not fair for my children to live in "poverty" when I pay that amount of money for child support on top of 100 percent of all health and dental insurance.