Consumer Redressal

I booked a flat on dated 28/02/2011 in Faridabad under 12 month time bound payment plan i made payment upto 10 month of stage as builder raised the demand giving me letter of due instalment but there is a clause.“ It is not obligatory on the part of seller to send demand notice regarding payment of instalment” Builder not complete the flat in 12 month he applied for occupation certificate in the month of July 2013 accordingly he raised the demand 11 month instalment in 23rd July 2013 but as per plan this instalment was due in 27-10-2012.this provision in other down payment plan every time he demand me according to this plan. I made payment in August 2013 Builder got occupation certificate in June 2014 accordingly he demanded me in June 2014 .Now the builder demanded to me penal interest as per my due time bound payment plan but i made all the payment as he demanded. Whether builder demanded 100% payment without offer of possession of flat