I have paid a 15k deposit cash for a flat price of 150k . My mortgage offer is 75% of the down valued valuation. I have to find a crippling amount of cash on top of the 15k i have already put down for a flat worth a lot less than 150k.

If you read the contract all the clauses are written in the developers favour. They can choose when to complete , when to serve notice and it is explicit in terms of what can be done in terms of non completion. The contract states how the purchaser can be sued and the levels of charges etc. that can be levied against the purchaser.

The only massive benifit in the purchasers favour now is the credit crunch which no-one could have foreseen. (force majour)

It wont look good for a developer to sue someone who has no remedy to the situation and who is not at fault

The developer will only let you get out of it if they get what they want and cant see any way of getting more i.e. you pay them some money and there is no way of getting more from you.

I am interested to know what type of flat have you got and what was the purchase price, what valuation have you had on it and what mortgage you have managed to get on it.