Admin fees ridiculously high

I recently took a Mango flight during which I had to travel with my golf bag - upon check-in I was then informed that I had to go and pay an additional R300 one way for my golf bag - but that it \only"costs R225 if I paid it only (which I obviously would have done if I knew about this policy) - so they're basically charging you an additional R75 \""admin\"" fee - for which you have to go que up and receive some unfriendly service for in any case... how can they justify that? No thanks"