FNB not honouring the iStore payment deal - Stuck with a huge charge on my CC

I purchased a MacBook online on the 9th of March using the FNB deal to pay over 16 months at 9%, I checked out using the specific Buy on FNB button and paid - received my invoice which confirmed the terms and the message after purchase was that it would automatically be moved to my budget facility in 3-4 days.

16 March comes and it's not done so I call to check and they say it will be escalated and I must wait 2 days. I called back the next day to check if anything had been done and was told it's with the credit department.

No news on 19 March I contact RBJacobs who refers it to the complaints department, who tell me I must send them a quote from the istore. I sent them my invoice with the payment terms on, to which they reply they can't use an invoice - they need a quote, theyve queried the iStore to get a quote and are waiting on the iStore.

So more time goes by, I contact the iStore and ask them if they can send a quote - they tell me to email them and copy in FNB - so I did. No response by the 24th of March so I talk to iStore again who say they've never heard of FNB asking for a quote its something thats meant to be automated (obviously).

Back to FNB's RBJacobs who said he's sorry and he will escalate it for feedback, that was 9:55AM today, 25th of March, no answer by 2PM so I check with him again and he says he will follow up - no news 4PM so I follow up again - it's now 5PM and another day goes by without any progress.

FNB messed up and now I'm probably going to be charged interest on this pending purchase on my straight facility because nobody is competent enough to do their job properly. I just hope this doesn't take so long that I get charged interest on the amount sitting in my straight facility.