FNB uncontactable

I am an attorney doing a property transfer on the strength of a guarantee by FNB to pay the bond proceeds upon registration. It is now five days after registration and the money has still not been paid. It seems to be impossible to get hold of anyone at FNB to talk to. I have never before had a guarantee where a bank has failed to pay out the same day or at latest overnight. There may be a reason but you simply can't find anyone to talk to.