I went back to school in my 30s and graduated 29 years ago with $14,500 in student debt. Became a single dad shortly after and never paid it back. they took any tax refunds I made but it still got up to over 30G. I had a judgement against me but it didn't hurt my credit. Just never answered the calls from the many collection agencies or paid a dime. Once collections are after you and you pay even a bit it starts a 2 year clock going again and they can take legal action but are toothless until you cave in and pay anything. At least here in Alberta it works that way.
A couple years ago the calls and letters stopped. Turns out Trudeau did two batches of loan forgiving and I guess I was one of the lucky ones. Never got a letter about it or anything but the judgement is gone off my credit rating and I have a pretty good score now.
Tell 'em to take a hike. They can't garnishee a disability cheque.