Interest charged on demand never sent to me

I booked a flat under subvention scheme in 2016, offered by builder Paramount Propbuild. Here the financial institution was Tata Capital. I paid the booking amount and after that the Tata Capital person came to collect my documents for loan processing. He took all my documents and sanctioned a loan of ₹30.5 lakhs. Builder did not send me the demand for the amount to be disbursed, I asked the Tata Capital representative, he told me that they will disburse the amount that will be asked by the builder and for the same reason they have got my loan sanctioned at a higher limit. I did not receive any correspondence from builder or Tata Capital, only thing I had was copy of BBA where it was written that I had to pay ₹28.63 within 45 days. After a year in 2017, I receive a call from builder asking me to pay up ₹1.29 lakh as I have not made this payment. I asked him exactly what is this amount so he told me to talk to Tata Capital. I called Tata Capital and they said that it is the tax amount and you will have to pay. Tata Capital person said that they have received a demand of ₹29.90 lakh and they have disbursed only ₹28.63 lakh. I paid the tax amount but the builder charged interest@24% on this amount, which comes to around ₹37 K. I talked to the builder to remove the said interest on which he said to give a letter, to which I complied and even after following he kept on saying that it will be removed but never removed the same from my ledger. As on date I have received final offer of possession and have also paid all the amount in June'18, but the builder is now asking for ₹37k interest and not budging at all. He is saying you will have to pay up. I asked him to give me the demand letter intimating me the demand of ₹29.90 lakh but they are not providing the same and are saying that you must have received it. Even after visiting him 6 times and more than 20 email correspondence, they are not providing the same and saying you must have received it. I am asked to pay for the fault of builder. What to do in this case.