Property allotted to me sold to someone and my money is not given bck

Case brief: I and my wife - as joint owners, booked a property (3 BHK flat) under the scheme called DevKrupa Avenue (B - 304) located Right on SP Ring road at Hathijan, Ahmedabad in Nov 2013 We paid a booking amount of Rs. 1 Lac. We wanted this property as we wanted to gift this to our daughter for her marriage - which we planned somewhere in 2015. The promoters (Sahjanand BuildCon Pvt Ltd) said that the property would be ready by Oct 2014. Based on these promises, we paid a further amount of Rs. 5, 90, 000/- in Feb 2014 (totaling Rs, 6, 90, 000). We dealt with one of the promoters called Harish (don't know his second name) - all I know is they belong to Swaminarayan group. Papers and agreements were signed in Feb 2014 - for which I’m yet to receive a copy. In May 2014 - when we visited the site, we were told that the property will not be delivered by Oct 2014 and it may be delayed - as we did not get the confidence that the property will be delivered in time, we stopped further payment and wanted to wait till we get the confidence. Even at the end of the year 2014 - we saw no progress and therefore we wanted to opt out of this scheme. The sales team at the site wanted us to wait for a while as - if any new booking comes, we will be given the money back. In 2015, our daughter got married and this property was certainly of no use to us - so we insisted to give our money back and asked for processes. We were delayed and given some reason or the other and it moved on till 2016. After a few heated exchanges, the promoters gave a form (cancellation form) and asked us to fill it. We submitted the form on 07 March 2017 - and are told to expect our money in a months time. We waited for 3 months (till Jun 2017) and after that when we approached, the promoters simply refused to meet us - every time, we wait for a considerable amount of time in his office and we will be asked to come the next week. Finally, in Dec 2017, we could get hold of the promoters and he said that the application form and our agreement that we signed in 2014 are not traceable - so he wanted to give him some time. Again in March 2018, he told us to give a fresh handwritten application form in Gujarati language - and he promised on his credibility that he would pay us in 12 days - but he would take 10% of the cost of the property (total base value of the property at the time of booking was around Rs. 20 Lacs) as penalty. We agreed to that as well and gave a handwritten application as per his request in Apr 2018. He asked us to wait for 2 months - which we did. From Jun 2018, he flatly refuses to pay us back - saying that we should buy this property or any other smaller property in that project. Recently a friend of ours wanted to buy a property in that area and we all went to see but we were told that it is sold to someone else and the builder has not informed us either. What are the options?