I have a plot in madni gardens.

I have a plot in madni gardens in khana chota sowa i have purchased this from a seller who have purchased it in 8 lac on installments i have paid 4 lac of own on this plot now i am paying installments of 20k per month and 632,000 are given and have to pay 120,000,0 have to be paid they are offering a half file on 15000 payment and i want to sell it on own what should i do should i sell it or pay 15000 to have an half file and then continue my installment??? It is near lda city kahna