Refund of paid amount

I Have booked a apartment in 2014. It is 27 tower township. While booking I had paid 20% of total amount and rest amount to be paid on possession as per signed application. Possession date is not mentioned in application form.As per application cancellation was : 5% of total cost before sanction of plan, 10% of total cost on subsequent to sanction / approval of plan / drawing, and 15% of total cost on signing of agreement for sale or receiving approval of plan. Builder told verbally that it would complete in 2 years. In October 2019 builder informed me that part OC has been received of my booked flat/tower and you have to paid balance amount. I told him that on the basis of part OC dont want to take possession and I want to cancel my booking. Builder replied me that as per signed application 15% of total cost of apartment will be deducted on cancellation as OC has been received. I told him that project is delayed and OC is not received it is part OC only give me full refund. Builder denied. Is it possible me to get full refund?