Well, the ICL isn't a source of legal advice for you. They're appointed to represent the children's best interests, which means they review all of the documents for the entire case, and give its recommendation to the court accordingly. They're not obligated to respond to questions either party has, just the same as your ex's lawyer isn't obligated to respond.
If you're seeking help as an SRL, the Family Law Registry and Legal Aid can help. Legal Aid will offer up to three appointments for free on a single matter, so write down all of your questions before your consultation.