First Bad Experience / Not Happy

I had an experience over the weekend where I was upgraded from Premier to Private Clients without any hassle within 5 minutes. It was not my intention to go through with the process, as I was only browsing the app and the "recommendations". When I realised what happened, I immediately contacted FNB on the Secure Chat and was informed that it would take 16 Working Days to reverse. It was only on Sunday, the next day, that I received an SMS notifying me that a credit enquiry was made on my credit profile.

In the meantime, FNB deducted what little funds were left in my account to pay for this upgrade, on a pro-rate base I was told.

How is it acceptable that FNB immediately upgrades me without any checks, but then it takes 16 working days to reverse the mistake? On top of that, I get charged for this reckless action. All I want is to reverse the upgrade process and be refunded the pro-rata amount that was deducted from my account.