• How to get back money paid to bank through RTGS

Dear Sir,
My neighbour house came to auction from Shriram housing finance for not paying housing loan for more than 7 years. I know the house owner Mr. Srini and contacted him to buy the property. We both came to a settlement. The house owner (Srini) informed Shriram housing finance (SHF) about this and Srini asked us to pay SHF a sum of Rs. 5 lakh towards first installment of one time settlement (OTS) to stop the auction process of SHF. Srini also prepared a hand written letter stating that on behalf of him, my father-in-law will pay Rs. 5 lakh to SHF for OTS process. My father in law also signed that letter in person and submitted that letter to SHF. Then my father-in-law transferred Rs.5 L directly to Srini’s SHF loan account number through RTGS payment.
After payment of Rs. 5 L to SHF, next day my father in law prepared a legal document stating this first payment to SHF followed by how we are going to pay SHF in step by step process and asked Srini to come and sign the legal document. Next day before signing, Srini asked to pay him another Rs. 5 lakh as advance. We told him the we will pay money to him only on the day of registration. But Srini didn’t sign the agreement prepared by us. At this juncture we got a doubt in his words and decided to stop the process with him as well as sent an e-mail to SHF that we will stop the OTS process. Few days later a telephonic conference call was arranged between SHF, Srini and myself. Srinivasan informed the manager of SHF, that he is not willing to sell the property to me. So the manager asked to stop the OTS process and asked me to participate in bidding process. This the manager asked us before itself, but since Srini is known to me for years I informed that I don’t want to participate in the bidding. Later, I decided (under my wife name) to participate in bidding and by god’s grace I won the bidding also. Within a month we paid the total bidding amount (March 2021) to SHF through RTGS. Meanwhile, Srini filed a court case in DRT against SHF stating that SHF made auction of his property for less amount. The case went for almost a year and recently judgement came (Feb 2022) in favor of SHF. 
My father-in-law already sent a legal notice to Srini but there is no response from him. Srini does not have any source of income to pay back 5 L. My father-in-law also asked the manager of SHF to repay our Rs. 5 L that we paid initially to stop bidding process. But manager refused to repay Rs.5 L stating the reason that it is credited to Srini’s loan account number in SHF. 
Our question is (1) whether it is possible to get 5 L from SHF to my father in law account. 
Currently, the Sale deed is under process for registration. 
(2) whether before taking the sale deed from SHF , do we need to file any case against SHF through my father-in-law. Will that handwritten letter by Srini and further signed by my father in law in front of SHF staff people can stand as evidence to get back Rs. 5 L from SHF.