Diversified Collection Services (DCS)

I have been being harassed by DCS. They have been calling me early in the morning, late at night, and at my job. I am an AmeriCorps national service volunteer and make a small stipend. I tried to have my student loan put into forbearance with AES, the original company I took out the loan from and they gave me the runaround and then put my account into default. I talked to them about the situation and they were very rude and threatening. I have found a lot of people online have had similar problems with both AES and DCS. They want almost $10,000, which is over three times what I borrowed. I don't know what to do.