Viv, you're getting all worked up and confused, but it's really quite simple. It seems that you can't force them to sell at the price you'd previously agreed. (Even if you could, your legal costs would far outweigh the benefit.) I think you are being confused and held back by thinking about the past, and dwelling on the deal that you thought you would be getting. It's really not relevant to your decision-making, because that deal was never finalised and it's no longer an option. Forget about it!
.
Dear ozperp,
You are right. I have been living in the past and kept thinking how wise was the decision I made, as the property's price increased remarkably after we signed the contract. I really need to accept the fact, see what option I have at moment.
I really appreciate your support.
Viv