Failure to produce certificates

I did my N2-N6 and graduated from this college. I received all my N certificates except for N5 and N6. I app**** for these certificates in 2018 and again in 2022/3. I haven’t received them and when I enquire about them it’s always a case of “let me check for you then I’ll call you back”. I’ve been waiting for them to call me back for 6 YEARS. I’ve went to the college personally to enquire instead they made me reapply. I’ve lost a couple of job opportunities because of this and they’re unwilling to write me a testimonial or something that proves I completed N5 and N6. They’re also not willing to hire me at the college or help me in any way. ☹️