FNB credit application department's negligence damaged my credit score

i've been an FNB customer for only 3 months now and i've never felt so harassed by any kind of business like FNB has harassed me.

when i opened my Premier cheque account with FNB they offered me a credit card, as happy as i was to join FNB i agreed to get their credit card. One of their consultants asked me to submit my work contract because i had just started to work, the following day another consultant called me and told me that i would have to wait for three months so that i can submit my three months bank statement because they couldn't use my work contract, "as instructed" i waited for three months and sent my documents through to them on the 24th of December 2018. To my surprise, i received an email from FNB showing that my credit card is in arrears and i also received a call from Lincoln and Associates telling me the same thing and i must make arrangements as to how i'm going to pay, mind you i've never even received a credit card from FNB nor a confirmation saying i have a credit card with them, and i'm already in arrears for just sending my documents. this messed up my credit record after struggling for years to keep a good credit record.

can anyone help me with a way to resolve such a matter and assure that it never happens to anyone else.