Standard bank is Unethicle

Standard bank is a bloddy *******. I took out a loan with them in 2015. The loan term was for 30 months wich was suppost to end June 2018. Last month the deduct R6000 from me. We I made the query regarding this they informed me that my loan was in arrears. Now I have never missed a payment. They debited my account every month, yet they state I am in arrears. They cant tell me at wich branch I took out the loan Prior to the end of the loan term no one could give me the outstanding amount. I then made an arrangement with them to pay off the remainding R6000 at R500 a month... they debited my account with an extra R244 to wich they claim is the interest. The consultent I made the arrangement with never mentioned interest once. I am so angry with this **** service from standard bank I will never bank with them again and would never recommend them to anyone