Constructing G+5 floors in a G+2 building.

Posting here so if anyone has gone through the experience may offer some helpful suggestions. I am a first time home buyer looking to buy a 3BHK and not sure of how it works around here (Hyderabad). So an acquaintance of my dad who’s a builder is looking to sell a 3 BHK in an under construction property that has G+2 floor permission. However, the builder is constructing G+5 floors and tells us that the permissions could be acquired at a later stage. Apparently this is a common thing that happens especially in the central parts of the city with independent buildings. The builder himself has a few finished buildings in the same area with flats that are all sold and occupied. We've know the guy since a few of years now. We went through the home loan process and the bank said that they would not be able to sanction a home loan for this one as builder does not have permission even though the floor that we are planning to purchase (2nd floor) is approved. They later on suggest going for NBFC home finance as the criteria would be a bit lenient there although the interest rates would be higher. I am not sure how common this is in Hyderabad. Should I go for NBFC loan? I haven't heard good things about it as they usuallly dont adhere to RBI interest rates. Should I convince my dad to not pursue the property at all? Like I said the property is quite good in that everyone in my family has liked the location, convenient commute etc. Also the builder is someone my dad is familiar with.