Builder doesn't give my money

I was visited Bengal Shrachi Housing Devepolement LTD. project Shrachi Dakshinatya at Baruipur, Kolkata as on 30.06.2022 at around 2.00 p.m. I was interested to purchase only one flat not any garage space. On the same day at evening around 8.00 p.m flat attendant Mr. Ranjan Patra came to my house with an Flat booking application form . He wanted from me a cheque of Rupees 87,043 . We both husband and wife asked Mr. Ranjan again and again that if any cancellation situation will occur then can we get our hard working money from Shrachi Housing Devolopment Pvt Ltd ! Brecause we are belonging lower middle class family and Rupees 87,043 is a life saving amount to us. Then Mr. Ranjan assured us, even helped me to calculate 5% of Rs. 87043, he told us definitely I'll get Rs. 87043 after deducting of 5%. Then we both husband and wife signed in an application form , provided by Mr. Ranjan. He give us a Money receipt also of Rs. 87,043 . After that Bengal Shrachi Housing Devepolement LTD. didn't provide me any allotment letter and not any agreement. Now due hardest financial crisis of my family I want to back my money but the Builder refuses to give my money they told me that Rs. 87,043 is non refundable because I cancelled booking and according their norms of joint venture no any amount I'll get. I was shocked and told them that Attendant Mr Ranjan assured me at the time of application form signature that this Rs. 87,043 is refundable after deducting 5%. But they ignored even Mr. Ranjan also refused his words also. I sent several mails to them from 16th August 2022 till today 9.09.2022. But I was disappointed Please help me and guide me that what can I do now? my family is in hardest problem of money . I am vey hopeless now. Thank you Kind Regards Baishakhi Bhowmik