Understanding Your Company's Process
First, find out what the actual process is in your company. Is it specific to you alone, or is it the same process followed for all employees in the organization? Do they have a process for issuing Service and Experience letters upon being relieved from the company?
What to Include in Your Resume
Never include anything in your resume except your educational qualifications, experience level, the work you have handled, the companies you have worked for, your personal details, certifications, extracurricular activities, etc. During the interview, address any concerns openly, be honest, and provide all necessary proof to support your experience. Mention that the offer can be cross-checked with your previous company. This approach will likely lead to a successful job application. However, why do you want to leave a government job?
Regards,
Babu