Account Frozen

I opened a Standard bank account for my daughter now 18, about a year ago.Only small amounts was transacted in this account, until last year December, when I deposited a large amount to her account, to cover for her accommodation expenses as first year student at Stellenbosch University. The funds were transferred from a overseas investment that I created with the aim of paying for my 2 kid's education .The Bank Froze her account when this money came in, because of what the call irregular activity. After sending them all the proofs and documentation the account is still frozen almost 2 months to the day.How can a Bank have this Authority over our money ????