Wrong interest charged by Builder in noida

Hi, I had booked a flat in noida extension area in 2013; first payment were made from my brother's account. due to this my loan were rejected saying that we can not make payment from brother's account. then i again paid this payment from my account. this took around 1 month delay. then builder did not provide us agreement on time; due to this again 2 month delay for disbursement. this all is lined up in mail with builder. Now builder has send final demand with interest charged for which they are responsible and they do not have OC/CC. after some months we have paid the final demand but builder has cleared other changes (electricity connection, PNG charges etc..). actually they should have first cleared the base amount. Builder is not ready to waive off the interest amount. Now they are continue to charge the interest amount and after 11 months of final demand they are not able to offer physical position as they only got PART OC. And some other charges (extra electricity load, internet connection) they have included which is not as per agreement and they are saying you have to pay this amount compulsory even not in agreement. Kindly suggest what action can be taken against this builder. Regards, Ankur Garg