Good on you for holding out, you've done what he requested. I reckon he is just seeing how far you'll go. We had this when we sold our previous house, but we stood our ground. We actually thought the sale was going to fall through, but he was playing games and waited til 4pm on Friday to confirm it. And then we had to chase him for the deposit. What makes it worse is that he is a real estate agent!!
Sorry back to you, hope it all works out for you Kaz