Exorbitant SLOW lounge charges because not using banking app!

In July my husband and I and our two kids visited the International SLOW lounge in CPT. This has always been a standard RMB banking reward, but I checked this webpage before leaving: https://www.rmbprivatebank.com/we-reward/slow-in-the-city.html It says QUALIFYING CRITERIA : RMB Private Bank Cheque and Credit Card, Registered for eBucks. Which implies that I have 12 complimentary visits a year.

When we showed our cards there were no warnings about charges (I signed nothing and entered no pin). Then my bank statement showed R2000 (!!!!) taken off my account. The argument is that we are on ebucks "zero" level because we do not use the banking app (but we do online banking). No warning, just a charge and a claim that I knew about this. As if I would send R2000 on a one-hour visit to an airport lounge!

On complaining, I have received really appalling service from FNB - it almost seems like a ****.