Shall we get the interest for advance money on a failed property transaction

We liked one property (15 years old house) which don't have any approval. Since we liked that property, I spoke with a seller to purchase that house. Seller said after getting proper approval we will have a registration and both are agreed. Seller asked us to pay 5 Lakhs advance as token (Cash) to sign the agreement.We to arranged the cash and agreement was signed on 1st oct 2019. Agreement Terms 1. Seller will get the approval within one month 2. Buyer should buy the property within 2 month from the date of approval 3. After approval if the buyer not ready to buy then advance amount not return Its almost 2 month 15 days, for that property approval is not received from govt side. Now seller asking us to do the registration without approval or get the token advance(5 lakhs) what we gave. We requested seller that we will wait for another one more month, but seller is saying many peoples are ready to get the property without approval and with higher amount why should i wait for you? My question. 1. What is the agreement validate period for property sales agreement 2. Whether we will file any case for this 3.Shall we request the rate of interest for the advance amount or not which we gave