My name is XXXXX XXXXX I'd be happy to answer your questions today. I'm sorry to hear about your situation.
Unfortunately, child support is one of the only situations that allows Social Security to be garnished. That limits your options somewhat. You could try to reach a settlement with the other parent, where you pay a lump sum in exchange for the forgiveness of the remaining debt.
If part of the amounts being taken are for current child support, rather than past due payments, you can file a Petition for Modification in the Family Court where the order was originally entered. The state puts the forms and instructions online, so you would not have to hire a lawyer.http://www.mass.gov/courts/courtsandjudges/courts/probateandfamilycourt/forms.html
If it's all for past due support, and you are unable to enter into a settlement, unfortunately, there is no way to stop the state from taking the money. They have a legal obligation to uphold child support laws, and their duty here is to the child, not the parent. I'm sorry.
I realize that you may be disappointed by this Answer, as it is not entirely favorable to your situation. However, it would be unfair to you and unprofessional of me were I to provide you with anything less than truthful and honest information. I hope you understand.