Ontario - RESP question.

[WendeeBee2003]

Hello everyone.  Hoping someone can help me or guide me in the right direction.

I've been divorced for the past 8 or so years.  Live in Ontario, Canada.  My problem right now is that my custodial ex is denying we ever set up a RESP (Registered Education Savings Plan) for our children.  

How do I go about finding out what happened to it?  I am 100% positive that we did set it up years ago with a certain bank but she is denying this.  

Do I need a lawyer to find out this information or can I check into it myself?

Please advise and thank you so much!