FNB short term loan

Good day I made short term loan on the 20th of November 2018 0f 7000 which would be returned with 850 interest. The loan will be paid back by the 29 of December 2018 to my understanding only to wake up to a shocking bank massage notification on the 23rd of November 2018. (So the money was in my bank account for 3 days only, not used yet) I took out the short term loan so that I will be able sort out a few things over the weekend. I did not even get a change to use that money that I borrowed yet I need to back it back with interest (3 days) with out me using it... It is unfair of the FNB to treat it clients in this manner. I have I have been ********** by FNB bank of R850. FNB SHOUD HAVE GIVEN ME ENOUGH TO FOR ME TO BE ABLE TO USE THE MONEY THEN PAY BACK THE MONEY WITH INTREST...