First things first.. Sorry that you are having such a problem with your deal... Please understand that we are only giving you opinions and not necessarily a legal opinion...
Now I would speak to the agent involved... Not on the phone, pin him/her down and find out what exactly the problem is with this... If you get the same reaction or type of reaction, then you need to sit down with the agent's broker... Now if I understand this correctly, you are purchasing a house that is being built.. Right... Another thing to do is to talk direct to the builder and find out exactly why he/she is having such problems... It sounds as if the builder and/or agent is being put in a pinch for something and they don't want to admit it...
Again persistence is the key... Good Luck and keep us posted...
Duane