Jds Infra Developer Pvt. Ltd. - Not getting refund

I have given **,*** to JDS Infra Developer Pvt. Ltd. to buy a property in Greater Noida. At the time of taking the money, they assured that the amount will be refunded if you change your plan before registry and your total amount will be refunded. I had some urgent requirement of money in April and ask them to refund the money and they agreed to return the amount after **% deduction (they assured ***% amount be refunded if don't want to buy the property), as I had urgency I agreed on that. But after that, their representative has stopped picking calls. I am calling at least twice a day but some are not picking the call and some numbers are switched off.
I am quite irritated from their behaviour and now I need my full amount back, please guide me on how to proceed ahead.