See if the property is under litigation and builder fails to deliver on the promise date then you can on ground of delay seek cancellation and refund of complete amount along interest.

You can file RERA complaint if builder fail.to refund on cancellation and fails to deliver in time.

Kindly clarify whether project is registered with RERA?

2) registration is mandatory for builder to sell flats 

3) check whether building plans ha e been sanctioned and commencement certificate issued 

4) builder can deduct maximum 10 per cent of booking amount in case of cancellation of booking 

5) builder cannot deduct 10 per cent of agreement value ie Rs 5.9 lakhs at time of cancellation of booking 

6) builder agreement cannot over ride provisions of RERA 

1. Yes you have every legal right to terminate the agreement and claim full refund of whatever you have paid till now with interest; as the agreement was based on misrepresentation of facts and also concealment of facts, which amounts to fraud being played upon you. 
2. If the builder isn't willing to refund; or is stating of some deductions (such clause may be in the agreement), then you must initiate legal action.
3. You can either sue him for specific performance of contract; or you can file consumer complaint in consumer Court. 
4. Of the two options stated in 3), which will be better can be suggested to you only on exhaustive consultation with me. I'm based in Mumbai/Navi Mumbai just as you are; so it shouldn't be much difficult for you to visit me. . 
5. I have handling such matters since more than a decade and am willing to take your case to it's logical conclusion by pleading in court as your counsel (Advocate) and making sure you get appropriate legal remedies for the troubles you have suffered

Yes if you cancel the booking on ground of delay in construction.

Builder cannot deduct the cancellation charges if he at fault. 

You should make a complaint against builder for refund of money with RERA regulatory authority.

You will have to file a Consumer Complaint against the builder for seeking possession of your flat and also for seeking compensation, damages that you may have suffered due to the delay and stop work on account of the builder. 

Yes you can apply for refund before consumer court or rera

This is my response to you:

1. Is it RERA registered?

2. If you have signed the costing sheet and orally accepted the terms then you are bound by it;

3. The cancellation fee can be levied;

4. You can send a legal notice first;

5. You can also take it up as a criminal matter and file a complaint under IPC to police station;

6. Consult a local lawyer, state full facts and take steps.

1. As per the information mentioned in the present query, makes it clear that though you don’t have the registered agreement but at least have the agreement as I assuming this and would supported by the signed costing sheet.
2. Yes, you will get your money back with interest in fact, but will have to approach the RERA Tribunal if the project is RERA registered or to the consumer forum.
3. This will take little time, but you will get your money back.
4. And the condition of deduction is only applicable if you are willingly cancelling the agreement without any fault at builder end, but here the fault is of the builder.
5. You should not be worried if the clause of “whose fault” is not mentioned.