Hi
The builder will need to get the occupancy certificate before asking you to take possession.
Since you have already paid EMI for last two years, slowly banks might pressurize you to get the registration done and handover the registration document to them.
So the best options would be
a) find out what the other occupants of the premises have done (they also have the same problem of deficiency of service by builder).
b) Please be informed that Occupancy certificate will be issued by Municipal authorities only when the building is completed and if there are deviations from approved plans, the penalties thereof are paid for. So from what you said and what i understand,it looks like OC will take atleast a minimum of 1 year.
c) In this context, look at the amount of money you have already invested and amounts that are payable by you. Do your own maths.
d) I suggest that you can do the registration,, provided builder gives you in writing(even an email or undertaking in stamp paper to provide OC and complete land scaping works) should be a proof for you in future.
e) Also almost all builders promise the moon and deliver barren lands. there is no builder who has delivered what he has promised. for instance 8 passenger lift. you might not be able to change this as the builder will say the property owners delayed payment of money and hence he needed to resort to such methods.
f) Once the building is occupied, form an association and fight such deficiency of service as an association.
g) But for now, tell him of the deficiencies that impact you the most(the wall plastering, doors, toilets... access to your flat .... basically the ones that impact your personal property and rectify the same.