My sister in law filed for canadian immigration for my husband on 1997 through an agency.When he was on vaction to his home country on Dec 2000 they called him for interview at NY.He has no idea abt it.On april 2001 he got a letter from agency stating that he has to pay 1500 dollars more.(according to their contract his sister paid 3000 dollars on filing time.the remaining amount has to pay once after he become an immigrant).We called them and said we didn't get any response from them reg interview and all.After that we moved lots of time to different parts of USA.We didn't get any response from them also.so we thought they closed that file.After 7 years, this week one collection agency send a mail to us stating that we have to pay 4500 dollars for that immigration agency.and we need to respond within 30 days like that.what we will do in this case.?we re applied for canadian immigration by ourself on 2001 october.we have all the documents for that too.how do we contact this agency?