Builder Cheated with Cash Money

Hi, I had a contract with a builder to construct my home. The builder sent an agreement initially for 2.15 cr, we signed and started work. I gave then 7 L via ACC and 35 L via cash as part of the first 4 stages of payment. Later on a different date we put another agreement for removing the cash part and this agreement is now for 1.75 Cr. After a few days of commencing the project, I came to know the seller had given away the project another builder (outsourced) for a Sum of 1.9 Cr. There were so many delays in construction and whenever I ask the person onsite they say they have not got the funds from the company. I raised a lot of questions. The company again asked me money and I said i cannot as I need to see the proof of work for already released payments and they said they will continue only after paying the next stage payment and I refused. After which they involved their legal team and I sent them a legal notice. Now they refuse to accept that I paid in cash and only claim to have got 7L. I have property whatsapp communication from their manager with the amount received for the total 42 L. the 7 L have company letter head and the 35 L have no company letter head. Question- I was not told this work would be sub contracted and It was left out to someone else? Is that whatsapp proof is enough that they got the funds from me in cash? What recovery options do I have?