BTech Diploma

I registered to what was advertised by xpert (before the merger - allaboutxpert) for a BTech diploma course in 2011. I completed all my modules and have not received my diploma. Upon enquiring, I was told that they have not received my POE which I had submitted. They later told me that they have no record of me confirmed that they have also sent my certificates for other courses completed through them. I said I have received no such (other certificates), which they are now according the them reissuing to me. I feel that they are contradicting themselves to inform me that they have no records of me, and that they have issued the other certificates (which will be reissued now). It is now 4 years later and they expect me to resubmit a POE that I no longer have. They also changed the BTech to a certificate course after it was advertised as a BTech diploma.