Account was approved and then later declined without notice.

I app**** for a credit card on Saturday 24th. I was approved and had to sign a contract. I was also given a limit. I was super excited about this. I then received a message which confirmed the account was open. It also appeared when I logged into my online banking. I then received a sms to let me know that the couriers would contact me regarding delivery. Today when I logged into my online banking, I noticed the account was no longer showing. I then called in and was told the account was declined because one of my existing accounts (wonga) is not old enough. I explained to the support person that wonga is a payday loans company and therefore now possible to have an account for longer than six months. The woman was extremely unhelpful and told me that there is nothing I can do but reapply in 6 months. I don't understand how an account could have been approved, all documents signed, limit given, courier information set up, and then declined. I've never once paid any of my accounts late and have been a loyal customer of FNB. I would like this sorted out as soon as possible. If not, my and my partner and the company he owns will no longer be banking with FNB. This experience has been so upsetting to me as it is was first credit card and something I was proud of. I will also make sure that I share my devastating experience. My partner and I are so dissapointed in FNB.