DCS COLLECTIONS GREAT LAKES EDUCATION, SALLIE MAE They keep harssing me about my student loans that went to collections in 2005 n/a, Internet

I went to school in 2004- 2005 ,had loans with salli mae which got changed to great lakes education.
I had set up payments with great lakes in 2005, but due to having cancer I could not make payments, so they gave me a 1 year extentsion.

Then in 2006 great lakes kept calling me everyday saying that I had a past due balance of $1000.00 and that I needed to make arrangementts, but I could not do anything.
The least amount that they were going to except is $300.00 a month, of I said that I could not do that.

After a while I did not hear anything until the last 2 weeks, from a compamy called dsc, they have threatened my lots of times, due to my loans and now there is a automated number that calls me everday.
This is wrong I cannot afford to pay anything back considering that my student loans are in collections.

These people need to be stopped.