Cancellation of offer of appointment.

I got selection through SSC Stenographer Exam 2010 as Stenographer III in Ministry of External Affairs, and got offer of appointment on 24.08.2011. I accepted offer of appointment and written them to ask my medical and police certificate from my office as I am working in central government service and demanded the same to my office and given to them by office in October, 2011 after that they issued me Joining Letter dated 04.02.2012 to join MEA but due to some personal reasons I asked them to give me 6 months extension time to join MEA. But, they did not give me any reply when I approached them to know what happened to my appointment. They replied that we will reply to you but sir, after lapsed of 6-8 months they did not replied me. I personally contacted them many a time but they did not replied me whether i could join MEA or not. I again given them representation on 11.07.2013 to issue me appointment letter and later in november 2013 and filed RTI on May 2018 and given reply that your matter has referred to DOPT for advised and cancelled my candidature on June, 2018 without citing any reason. What should I do now under these circumstances?