Shot term loan

I took a loan this month because my father passed away and the insurance took time to pay and we were supposed to bury him. I then receive money from the insurance so I paid the initial loan and then ask the consultant if the bank will like decrease the interest that they charge me since I paid the initial loan before the 24 months that they gave me. then the consultant said that's not possible because I've already already took the loan so they will continue debiting the money until the contract end so now what I want to know is how is that possible, I know that I'm supposed to pay interest but doesn't the bank have to reduce the money since I've paid the initial loan? I know I am supposed to pay interest but I was looking forward at the bank to tell me that they are going to reduce the interest that's all that I'm having a problem with. the fact that the consultant couldn't help me is bothering me