I'm not sure that's what duress is. Sounds like moderate discomfort and squirming in his chair.
I also don't think you should ever sign a contract without a real lawyer advising you. "I'm sure the mortgage company will just give me a better payment if I can't afford it."
100% agree on the lawyer part.
I think a lot of getting the $30k back would have to do with whether he agreed to binding arbitration or not. If he agreed to that they would likely pursue it but if they had to go to court not sure they would.