DUT don't want to release my Certificate

I think I made a mistake by studying at this institute. I was supposed to get my Certificate in May after graduations, Now it's July, no one respond to my emails, calls, dms. Since contacting them. I would never recommend anyone to this institute. I'm applying for employment, most companies want to see the certificate, but now I'm unable to get that opportunity, because you guys you don't want to release my Certificate. DUT your Customer Service is poor.