Slow lounge - client fee acknowledgement

I checked into the FNB Slow Lounge with a guest. No mention was made that there will be a fee payable and we were both allowed in. I now see that the slow lounge fee was not reversed from my credit card. How can you charge someone for something without telling them ? Surely if I needed to pay a charge this should be mentioned to me while checking in ? Seems the reason you do this is so that you can charge customers without their acknowledgment which isnt right. I would like this fee to be reversed.