I read a book a long time ago entitled "Stop It", it's all about debt collecting, their tricks and tactics and how to stop them and deal with them. There was a chart in this book that mapped a deb collector's expectations of collecting the debt and how much they anticipate to collect as time goes on. At only 6 months after you default, the expectation was alredy down to 50% of what you owe and steadily declined after that to near 0% at 1 years time. You said it has been 4 years. Offer them 5%. Tell them you don't work and that this is all you can afford. They will want you to beg, borrow or steal to pay them off, just keep saying that 5% is all you can afford and don't waver. If you tell them that you don't work and you are in school they will be very likely to take what you offer because you are essentially judgement proof. You don't HAVE to answer any of their questions either. You don't HAVE to tell them where you work (if you work) or what you own, they WANT you to tell them so that they can assess you money-wise and it also makes their job easier if you voluntarily give up the information. The only time you have to give up this info is if you are sued and the court orders youto submit it.
My parents got sued in NYS Supreme Court for breaking a lease on a piece of farm equipment, the amount they were seeking was around $12,000. They had every right to collect the whole amount too. But my parents had just sold off their farm (which is why they broke the lease) so they had virtually nothing, no more income from the farm and no assets to seize, so my mom made them an offer before the court session of 2.5% and they ended up settling at 5%. So it can be done.