Cancellation of Apartment Buyers Agreement after 80% payment in Godrej 101, Gurgaon

Hi, I will be grateful if I can get some guidance on this. I had booked an apartment in Godrej 101, Gurgaon couple of year back. I have paid 80% of cost of property by now. I now wish to cancel my booking but Godrej is enforcing a cancellation fee of 20% cost of property + 18% GTS (on 20% cost of property as its their profit after cancellation) + all taxes paid till date. I have read the entire "Apartment Buyer's Agreement" thoroughly and I cannot find any clause on "Cancellation by buyer". The only clause on termination of contract is - in the event of default by the buyer (the developer will charge "earnest money" which is 20% cost of property) and terminate the contract. My query is - in absence of any clause of cancellation of agreement/booking by buyer, I should not be paying cancellation fee of 20% cost of property as that's applicable only when the builder terminates the agreement due to default/non payment by buyer. Is that correct (or the absence of cancellation by buyer clause means that the buyer does not have the right to cancel)? Your advise will be greatly appreciated. Reg, Apurva