Deducting money for failed transactions

No FNB Ebucks, no! I purchased a Udemy course, was sent an error stating that there is an issue and to try later. I try again, same error message. I try for the third time, says i have been doing 3 transactions. but the other 2 failed. i now see a deduction of R50 x 2 for courses that i kept getting an error saying , please try again.