Fnb block Minor children's fnby accounts

Fnb has block my 2 minor children's fnby accounts. When I called them I was informed that my children's accounts is being investigate for *****. I was shocked to hear this as my children are aged 7 and 11 and their accounts are only being used for pocket money. There is not even huge amounts goining into those accounts, so how is this possible? The fnb consultants I spoke with couldn't give proper information and told me to call Bilal Mia who is investigating my children's accounts. The number they gave me is not working and it's decommissioned. I emailed this Bilal Mia but got no reply and the Fnb ***** line can't help me. How is this possible? How can fnb investigate Minor children's fnby accounts without given any reason or inform the parents. This is ridiculous.i have been a client of fnb for years and now I'm totally disgusted by this situation. This Bilal Mia is not reachable and Fnb is doing nothing to assist me. What kind of ***** is fnb investigating on a 7 year old and 11 year old accounts.