I worked in a company in 2009 for one year under a bond for training and employment. The bond period was 4 years. However, I resigned from the company within one year by paying the bond amount and reclaimed my educational certificates. At that time, the company did not provide a service certificate. Now, I am requesting it, but they are not responding. I have sent emails and made several calls to HR, but have not received any response. How can I officially obtain the service certificate? Please advise.