Building Loan Money Paid to Wrong Account!

My husband and I have a building loan with FNB and have to put through progress payment draws for various stages in the build. Recently we put through a draw of almost half a million rand that was paid end of July to the WRONG PERSON/WRONG ACCOUNT.

Waited a few days for it to reflect so we can pay our builders/suppliers etc (none the wiser) and then eventually phoned to find out and was told this! It is FNB's mistake and yet we are still waiting for the money whilst our build has had to be put on hold.

I was told that FNB is working on it (since beginning of this week) and then I'm told this morning they are waiting for the person to pay them back first?! Not actually our problem; FNB has to sort this out separately and pay us the loan money.

The best part of all this is that its been added to our loan account already and we had to pay a huge amount just in interest, which needs to be re-imbursed as well.

How does it take 4 days and counting to try and sort this very serious issue out?

Not Acceptable.