bond settlement

I finally have a buyer for my property and I already gave notice in the starts of April. For the last two weeks my managing agent has been trying to get hold of someone in nedbank so that she can settle my bond but no one gets back to her. She sends emails almost everyday and no response. In the mean time I've been handed over to lawyers and the settlement keeps increasing. My buyer is becoming Despondent because he Has already paid in cash. No one at nedbank is willing to assist with this sale. I need urgent help!!!!!