Defaulted student loan

Okay, I have defaulted on a private alternative student loan. The loan was originally with Chase (TERI loan) and now it has ended up with NES as the collector. I want to make arrangments to pay but they wont have it. Can they still garnish my wages for a private loan? I live in Texas in case it matters. I am confused and dont know what to do as they will not take the payments that I can afford.