Absa
Account security

I opened a 32 day call account for my children years ago. I am the only signatory on all the accounts. It seems that my 18 year old son went into the bank and gave the 32 days notice to have the funds released.
Absa security is a joke - how can my signature be the only authorised signature and they release the money on someone elses command?
To top it all the notice was given at a branch that does not even hold the account. This is pathetic ABSA!