garnished; please help!

i am about to be garnished by a private collection agency. I called them to explain my financial hardship but they refused to lower the percentage at which they will garnish me. It is at 25% but is there some way i can prove financial hardship to lower that percentage to 10-15%? I don't believe a company can garnish me and my family when we have such little expendable income as well as other debts we are obligated to pay. Any help is much appreciated.