Runwal Deduction of GST for refund booking amount after cancellation

Hello Sir/Madam, I had book runwal forest property in June 2020 since now there was no stampduty and registration done yet. when i booked flat that time builder mentioned possesion will be in Dec 2023 but not they revised possesion to Dec 2026 and i can not wait so long therefore i canclled my booking in Dec 2021. i send email to Relationship manger for cancel my flat booking and give my money back. when i send email initally they said refund will get 5-6 month process but after saying them RERA guideline as 45 days so they ask me to collect my cheque around 35 days. when i saw cheque there was around 68,000 deduction and RM said its GST they deducted I have total pay 2 amounts to them 1. token and then 2. after 15 days amount booking amount as i selected 5:95 scheme. but they generated 3 invoice and there is 3rd invoice of GST that i havent paid to them. Now they saying GST is not refund. but when i check on google they can still file and adjust retrun for Year [deleted] till 28th Feb 2022 as goverment extended. I have few question please answer. 1. as stmapduty registration not done so builder can still deduct GST ? 2. can builder dedcut GST for payment i have not made to them ? as i didnt not paid 30 days amount but still they generated invoice. 3. is there anything that builder can ajust and file GSTR-9C by saying booking cancell and get refund and giveme back