personal loan interest rate calculation.

spygirl

About to ask a very silly question, but hoping you will go easy on me.

I took out a personal loan, the credit agreement specified x amount of payments weekly for the specified period of time.
Also stated cost of credit as x.

weekly repayment x number of payments is equal to this amount. So far all is grand and I understand that perfectly.

However I am also being charged interest every quarter on top of this. Overall this is increasing the cost of the loan far in excess of what's in the agreement.

so instead of paying back say 24,000 on a 20,000 loan as stated in the agreement I will pay in excess of this. Going by current amounts charged each quarter to date, roughly 5,000 than i had expected to pay overall. Bringing overall cost of credit to almost 9,000.

I've also been ploughing extra payments in regularly to get loan cleared earlier, save on interest etc, but am worried I'm paying a lot more for the cost of borrowing than I was told.

What did I miss in the initial agreement? It's a variable rate but the changes haven't been so high to account for an additional 2,300 in interest so far.

Any information you can give me to understand why there are extra quarterly interest payments on top of the loan repayment amount/cost of credit outlined in the agreement.

Thanks, and apologies if this is a really basic question.