Supertech — booked a flat in sector -74 cape town in crown towers

I booked a flat and paid 10% booking amount in crown tower sector - 74 which is under construction and at the time of booking they never mentioned that you have to take subvention scheme plan so now they are are forcing me to go for subvention. Please help & suggest me what are things should i keep in mind while finalizing further or else tell me any way to escape and refund my money back