Appropriation of funds by FNB

My wife penned an account for our daughter when she was born 6 years ago. The account was linked to my wife's current account and we put some money as savings into the account. Earlierbthis year we checked the account to get a balance and found out that the account was closed by FNB themselves due to non-activity on the account. Furthermore FNB cannot confirm which bank account the current balance was transferred to. We tried phoning the call centre but no-one could help and they insisted we go into a branch to resolve the issue. We went to the Cresta branch for help and after explaining the situation again, the teller made us fill in forms and promised the money would be in my wife's current account at the an d of May. Its now 21 June and may wife has not received the money yet and no help from FNB. Why would FNB close an active bank account with a positive bank balance? Secondly why was the money not transferred to my wife's current account which is the nominated bank account?