Describe your Debt Load! - NCO out of Alberta and other student loan problems

I was a student in 2003 and due to OSAP removal of funding I was forced to leave school without my degree. That being said I found myself in deep about 60000 and the only way I could see the light of day was to file for bankruptcy. I did that and was assured by my trustees that once I was disharged that the student loans people would contact me. well they did and I started to pay them back. Only problem was that not all of them contacted me. Nearly 4 years later NCO out of Alberta contacted me telling me that I owe the Federal Government 20000. I told them no I don't I am paying cibc my federal loan. They finally convinced me that I owed them that money, but I disputed the interest that had been charged to me in those 4 years. I ended up having to get my MP involved and that was resulved now after that was settled I began payment now every 6 months they harrass me for more money because I can't make the minimum payment of 486 per month. I currently owe 14800 and my wife was able to find $6000 to offer them as a settlement as we wouldn't be able to pay both the remainder of the loan and the $6000. Here comes the question. Is it true that the Federal Government will not accept any offer? I am nearly at my wits and dealing with these people (using that term lightly). THey actually told me they would take the $6000 and reduce my payment to $50 a month so that I could pay off the $6000 and then resume normal payments. Do the math that doesn't even make sense. Anyway Does the government take settlements and if so what is the percentage of total debt that I would have to come up with? Also if I stopped paying all together anyone know how much of my pay check they would garnish. And Final question. Having your student loans with NCO as long as you make a regular payment how much damage does that do to you if you want to start building credit because I want to go to my bank and see if they will consulidate my loans for me and I make them one payment for 3 loans.