Delay of Govt Job joining orders after selection process is over

I have selected for the post of Postal Assistant(CO/RO) in Andhra Pradesh Circle against the Notification issued by Department of Posts in the month of Feb,2014 and Results announced in January 2015. After this Certification verification done in Feb 2015. But Among the selected candidates only some candidates have got their joining orders in April 2015 and acquire 6 months service, drowned 6 months salary and put remaining candidate in abeyance. My questions are: 1. All candidates written same question paper, applied to same notification, circle office, same state then why govt issue joining orders to some and abeyance the remaining? 2. When Vigilance Investigation going on recruitment how Govt issue the joining orders to only some candidates that means remaining candidates selected in wrong way? 3. Is there any constitutional rule about recruitment process and exact time stamp for complete the recruitment process and gave joining orders to selected candidates? 4. Can I file a case over this issue? 5. Is there any rule that govt pay the salary, give service to abeyance candidates? I hereby begging you because even Prime Minister of India did not give answer and solution to this issue. I tried in all the ways but no response so i can expect solution to my problem from you respected lawyers