Pearls city sector -104, mohali
Excess interest rate on delay payment

I have booked one plot in pearls city sector 104 in march.by depositing 15% of the total value of plot.company promised to delivered plot after 2 yrs.but till date they are not handover the plot.i have deposit total more than 85% of amount but i have not follow the payment schedule as development work is also not on that pace.result they still not able to handover the plot after 3 yrs.

now they send me demand notice of 798243/- as interest. pls. suggest what can do for that legally against them.