INTEREST INCREASING MONTHLY

I made two purchases from Makro in November, mid December downloaded my first statement, end of December paid more than what installment was due. Checked my statement in January, amount allocated for interest alone has almost doubled that of last month yet my closing balance this month is lesser than last month. Consultant was rather making reference to other amounts such as protection fees etc on account and if I over pay what my installment is it goes to my balance amount.

At the end of the call she could still not explain to me why my interest payable this month is more than last month, instead I was told that some months you'll pay lesser and some months more interest!