Credit Card Hidden Interest

I am so angry and furious with Capitec Bank, I had R1200 on my credit card and the past Sunday I went to pour petrol for an amount of R489,25 the next thing when I check my bal on the credit card it shows me that I have R179 remaining of which was very *****. I logged in to view the transactions history only to find out they are charging customers insane interest, each time you buy using their credit card they charge you interest of out R376,61 of which I was never explained about and even if they were explained how can they charge a customer so many interest in a day. I bought chicken licken for about R76 and they charged me another interest of R91,00 what nonsense is this Capitec up too. They are charging interest on the funds that are available for me to use. If you are out there thinking of taking up a Capitec Bank credit card I would advise you rather not.