Unfair treatment

FNB Temp loan approved and deposited on the 22 September 2018 and on the 27 September 2018 the amount of R1995.00 was taken back from my account without any communication and yet their loan agreement said the money will be repaid after 31 days from the day it was borrowed.I called the customer care & was told thats how the loan works.They take the repayment anytime as long as the funds are available in my account.I have been inconvenienced dismally,i borrowed the money to fix my car & the same day i took my car for services FNB decided to take back the money without any notification and left me stranded.They do as they please on my account.So disgruntled..