For the fulfillment of the contract between you and the second party, it is advisable that you file a civil suit against them for delivering as per the terms of the contract i.e. suit for performance of the contract. if there is an arbitration clause mentioned in the agreement between both the parties, then the dispute at first shall be handled by the appointed arbitrator as per the terms of the agreement. However, before you proceed further with the suit or the arbitration, it is advisable to send a legal notice demanding them to register etc and fulfillment of the promise.
You may proceed and deposit the received cheques for clearance. if the cheques are bounced, different story would come into picture as you may have to file a negotiable instrument case as well.