Since you live in Canada, and our expertise is only in American debt collection topics, however, I can only share the advice I would give you if you lived in the U.S.. I can't tell you if it works the same in Canada.
1. Order your credit report(s). Debts that are less than 7.5 years old will be listed there.
2. Find out what the statute of limitations is for the type of debt you owe. In the U.S., this is a matter of state law.
3. If the debts listed on your credit report are not outside the statue of limitations then contact each collection agency in writing, asking them to verify the debt.