Developers not refunding the advance money.

I had given a token amount of 1 lakhs cash in July last(in person, have a receipt for that with a witness) for a plot worth (69 lakhs ) in HMDA layout from the developer party agreed to pay full payment in 45 days, and go for registration. The next day I identified a mismatch in plot numbers in DAGPA, and the HMDA layout(The layout structure is the same, but the number allocation is different(for 2 plots, including mine) in the DAGPA & HMDA layout) and informed to the developers. Then they executed a Supplementary and Rectification Deed to match the HMDA layout(It took 2 months) with the land owners(It's an undivided property of family members(wife-69Yrs and 4 children-35-45yrs) of a deceased person(75Yrs), who was the actual owner) As per the token receipt instructions, I transferred 20 lacs through RTGS to one of the developer's accounts in the first week of Sept 2024 (the developer party has 3 individual members) obtained an agreement of sale from the developer party, and went for the bank loan for the remaining amount. The bank's legal process identified that The so-called legal heirs did not have any valid legal heir certificate from the civil court and the DAGPA executed with A notary at I special magistrate and asked for a legal heir certificate. When I asked for this document from the developers they mentioned to me that land owners are in the process of getting it and asking to wait. Now, Can I wait until I get it? or cancel this sale of agreement? I intend to cancel the sale of the agreement due to a few reasons which I think would be an issue in the future but I like the property unless this legal issue. *** What I should do if they don't give me full advance, what care I have to take to wait for that process - kindly provide your comment on this. *** Risk factors: 1. That HMDA layout (drafted around 2022 - final approval got in June 2024) is obtained finally through a Single window process(I think it is a kind of self-declaration. I think HMDA is not responsible for any legal issues) 2. Person X who passed away in 2021, and their so-called legal heirs still have not obtained a legal heir from civil court, and saying its in process. 3. It seems the developer party borrowed the amount from the other party for development and had pressure to repay and had clashes among them. I think they used my advance amount and so said to wait a few months. Thanks in advance.