What is this Finance charge/fee on my credit card Absa?

Now for a few months Absa has charged me a Finance fee/charge of R1033.13 for the month of 29th June 2019 on my Credit Card, OVER AND ABOVE of my monthly instalment.How does this work? For example: it's like going to a shop and i purchase R1033.13 worth of goods and i pay with my credit card. So it goes of my credit available, right? It's like Absa spend on my behalf. Then they send you a sms to say that i am overdraw on my account, i must pay it to use the facility again. I have always pay my installments on time and sometimes pay more than my minimum instalment. I did not sign up for this and nor was i informed of this. So many other clients are experiencing the same problems. It's besides the normal charges and installments. Absolutely ridiculous