Case Description

I have 2 sons. My oldest son is turning 18 this March 13.
My youngest is 15
His mother and I have been divorced since 1998
We were divorced in Quebec (Hull)
I have lived in Ontario since 1998
A maintenance order was made in 1998 for a ridiculous amount of child support(ex-wife wasn't working at the time) however we came to several agreements on our own which were written out and signed by both of us and a witness. I have always followed these agreements. They were however never filed in court. (a mutual decision since neither of us could afford lawyers) so the original order from 1998 was never modified by the court.
Since 1998 my ex-wife and I have signed 3 different agreements between us the last of which was signed in 2003 and was signed by both of us as well as a witness.
Last week she sought advice(for what I don't know) from the Quebec maintenance enforcement department.When the Quebec maintenance enforcement agent called me Monday morning, she said I was being served with papers by them demanding $25,000 in back child support(economic increases).She claims our agreements (between my ex-wife and I) are not valid and that I owe cost of living increases ect .
I have been paying my ex-wife between $600 and $650 per month since 2003. Between 1998 and 2003 the amounts varied depending on our agreement. Child support has always been paid.
In addition to these payments I have also spent tons of money on other things for them such as clothes, laptops, ect. which I am not complaining about. I work in a University and one of the benifits is free tuition for my kids. (which is taxable. Basically I need that original order set aside and these agreements between us honored.
Thank you