Intrest on late payment

I booked my flat in Dec 2013 at Pavel. I was virbally promissed to give my flat possession in Dec 2014. I had paide the first cheque of booking amount as demanded by buider. Therafter I didnot get any letter aur mail from builder regarding progress of my flat. 7-8 months latet i got demand letter stating that 40% of my building is completed and i have to pay this much of amount. I that letter intrest of late payment was also included. Iwent to builder office and quiried about this. They informed that 2 demand letter were raised and come back undelivered. I asked tham that then they should have e-mailed me. They said that u dont wory i trested will be not charged later on. After that I registered my flat on 13 Dec 2014. The documents were already prepared by builder and they send me to an agent in registet ofice, i did what ever i was told and didnot given time to read my agreement. After that got bank loan approval and paid to builder as per demand. After which when ever i was demanded money i gave through bank. And simultaneously i kept on aking about work complition. Now in nov 2016 i got letter of 100% work complition and for final satelement. In letter i am charged about 90k intrest. I went to the builder and had a merting with him and i said that sir if u r aking panely for late payment i trest @24% then am also entitled for intrest of the amount i have paid to u and for geting my flat ready 2 years late then the lromised time. He told that do i have any proof of promise that flat will be delivered in 1 year. I went to sales office and meet the same sale girl and asked that wether she has promised me to give possession of my flat in one year or not, she said yes we promsed. I made audio recording of that. What shluld i do... The simple that is that sir, i dont have money to pay intrest and i dont want to because according to my concense we both r wrong some where then why should i be chareged. I leave on rented house for 2 years due to late i possession of my flat and paid 8k per month. Along with bank intrest. Please suggest accordingly