Refusal to refund money mistakenly deposit

I mistakenly deposited R735000.00 into Drs Du Buisson Kramer Swart Brouwer, now called Ampath's account on 13 Aug 15. I immediately informed them of my mistake. They requested I email them proof of payment and my banking details which I did on the same day. I was assured by Dineo from Ampath's Accounts department that I would be refunded. On Monday I called again. This time I spoke to Liha who assured me I would be refunded in 48 hrs. My lawyers have been calling all week with no success. Nedbank, my bankers, informed me today that Ampath have refused to refund the money. Today is the 24th. What happened to the 48hr promise? This is a lot of money meant for payment of a unit I am purchasing. <br> I don't know what to do please help me!!