Refund of advance plus interest due to failure to receive IOD.

We deposited on 23.1.2013 and 16.2.213 total of Rs22,42,208 to buy 1bhk + 2bhk from JC homes Bhatani Riyo at Mira road . Miss Arti (VP) in their Santacruz office of JC Homes promise that they are going to start the project within six months. When asked the documents like IOD and others, she promised that they are reputable Builders and there is no problem.Their directors are top in the construction industry. After collecting our funds they drew an agreement that if within 18 months they do not start the project , they will refund our deposit plus interest @15% from the date of payment. Month after month started passing by , but there was no IOD was received from the authority. Rather they pre-launch a fake project covered under their reputation. Each month we go to them to up date of project and a new date is given for take off. On 5.7.16, we decided to ask for refund which they agreed to pay with interest. They are going to give post dated cheque dated after 14 months. This has left me under shock. I am cardiac patient with three stents in my body system. Being so much confused with Bhagtani Builder who have turned to be fraud. Please show me a way out to get my refund can be collected.