Do you happen to know how to resolve visa issuance delays?

Hello! I am a foreigner who will soon be going to Korea, but I am facing a lot of worries due to visa issuance. I am currently preparing to depart from Pretoria, South Africa to Korea, but I am in a really tricky situation due to visa issues. I sent all my visa documents to the Korean Embassy on January 22nd, but the next day they said there was a problem with the tuberculosis (TB) document, so I had to fix it and send it again. However, even though the courier company confirmed that the documents arrived on January 28th, the embassy says they haven't received them. 😢 Today (February 5th), I reprinted the documents and sent them again, but the embassy says they haven't confirmed if they received them today, which is making me anxious. I already have a job confirmed in Korea through the EPIK program, and I need to arrive in Korea before February 19th. If anyone has experienced a similar situation or knows how to resolve this issue, please advise me. I am really worried about missing this opportunity if the visa issuance is delayed. Thank you so much!