Collection agency troubles??

I just got off the phone with windham prof.(Which i do not recommend. Rude alot of threats and not very curteous). My girlfriend has about 5000 in debts from umass lowell that was sent to this collection agency. I called to see if there was any deals I could work out with them. We worked out a hundred a month.But he informed me that at a hundred a month, the school will eventually take the debt back, tack on another 45% and either send the debt to an attorney or to another collections agency. I then asked to get a monthly statement so that my gf can keep records of her payments, but the representative refused to send any documentation and said collection agencies dont send statements out. He said I can call and check the balance monthly with him. I would rather have documentation. Is that legal or is he just being difficult? I never heard of a debtor not sending monthly statements.
Now if they tell me that even if she pays the 100 a month it will still be sent back to school, why pay hin at all if the end result will be the same? I need help asap. She also has another debt with another company, i was advised by this site to set up a rehabilitation program. I did that and its working out. Thank you for the advice and thank you in advance for any responses regarding this issue.
thank you