confused about scotiabank loan

Hi, I've been following this website for afew years now.  I think it's time I post my problem. I'm hoping that someone can help me with my issue...I took out student loans back in 1991-1996 while attending the University of Toronto.  I made payments after graduating, but then I moved to the US in 2000.  Several months after moving I received a call from a collection agency telling me that my Scotia student loan had gone into default.  They threatened to ruin my credit history, and not knowing much about collection agencies at the time I negotiated with them and made arrangements to pay off approximatey $5,000. The agreement was that the collection agency would not report their involvement to the credit bureau if I completed the payments.   I sent post dated cheques (I cant remember which agency) and the payments were made. I thought I was paying my entire loan off and no record of the debt going into collections ever appeared on my credit report.  I returned to Canada in 2005 for one year and my income tax refund of about $3000 was taken by the goverment. I was shocked and called CRA. They informed me that the amt was taken to repay the federal portion of my loan still owing. I moved back to the US the next year (2006).  Now it's 2006 and I'm getting calls from Nordon collecting on behalf of Scotia stating that I owe $47,000!  Well i explained that i had already paid the amount off  in 2001, and the government took their portion from my income tax refund.  Of course they said that was not true and wanted proof. Unfortunately I never got a letter and had no proof.  I attempted to get copies of the cheques I sent, but was told by the bank (which had now been taken over by another bank) that they would have to search records for the cheques (back then nothing was computerized like now),and they would have to charge me per hour, and they had no idea how long it would take to do the search. So I gave up on that and since then I have been dealing with collection calls from Nordon, CBV  and NCO. They keep rotating. I returned to Canada last year with no plans to leave.  Last year I contacted CRA and they confirmed that I no longer owed anything.  However, I am still receiving calls from collection agencies.   Right now it's CBV.  I dont know how to get them to stop. I think they got my contact information from my credit report because when I applied for a report, I had put in my new address and phone number (big mistake).  I usually avoid them or return their letters which had been sent to my parent's home over the years.