Company not issuing experience certificate

Hello there, last year I was pursuing my Diploma in food production an 18month course but due to covid it was cut short. We were supposed to go through industrial training and bring back the training certificate so the college (institute of hotel management, Dehradun) could issue me my diploma, cut short due to covid it was a 16weeks training but my placement coordinator Mr. Himanshu told me and 5 other students that we will get training in barbeque nation hospitality ltd, Gujarat region. But afterwards he told us we will be getting jobs and got our offer letters so when we reached Gujarat we told the regional HR Mr.Hardik the same. Now the 16weeks have been completed but Mr.Hardik refuses to give and kind of experience/training certificate and says only after working for 6 months you will get one, My placement coordinator Mr.Himanshu refuses to take any kind of responsibility and says to continue for 2 more months but we were told it was only 16weeks and its not fair that while my others batch mates are done with their training, I am still doing it. What can be done in this? How can I get my certificate? Please Help me, I have so much pressure build up in my head.