Refund of Booking Amount from Builder in Gurugram

Sir's, I have booked a commercial unit with a builder in Gurugram on 26.02.2021 after oral discussion held with the company official and property agent. Both the persons promised that 24% annual return is guaranteed for a period of 2 years from the date of payment of 50% of the total price of sale. On 28.02.2021 i visited their fair again for negotiation and due to paucity of time they presented their agreement which i could not read fully and signed. The officials i.e. company manager and property agent excused that the signing authority has left and there is no one available to provide the photocopy and promised that they will send me copy of the application form duly filled and signed later next day to my office. They took my signature on a blank application form. On 01.03.2021 i called the property agent and he claimed that today is success property and 2.03.2021 is holiday and on 3.3.2021 he will send the application form as promised. Within this I started to feel that there is something fishy and started to read the application form as i took the photographs on my phone on 28.02.2021. I found that the agreement says that possession will be given on or before June 2022 which is 15 months from March 2021. By now i recalled all their actions and called the property agent on recorded line from my phone and he confirmed that they both assured me 24 months of rental on the 50% amount paid of the total sale price i.e. almost 25 lacs. On the same day i.e. 5.03.2021 i sent them a letter asking refund on their default and false promise. On 06.03.2021 the property agent called me and gave me option to wither buy the property or else booking amount of INR 5 Lacs stands forfeited. I started to explore the contact details of the owner of the builder company, on 11.03.2021 i sent a request letter through WhatsApp to the Director of the builder company but till date there is no reply, although he has seen my letter in .pdf format. My withdrawal is on the basis of the false promise and unethical and unfair trade practice by the builder company through its official/s and authorized channel partner. There is no single fault of mine and I can even show that i am in possession to pay the complete amount in 2 days, if required to show in Rera Adjudicator or court etc. but do not wish to proceed to but the property now as i see the real bad face of the builder in the very beginning and what not they will do later. Kindly advise me with the professional legal help.