Accumulating Interest Rate

Last year 2016 when I bought a car my contract stated there wont be any change in my loan application, I was surprise to receive email saying \You are hereby noti f ied that the interest rate pertaining to your agreement has been increased because of a<br> 0,25% increase in the prime lending rate\" by this time I was paying R3100.00 and I've been getting this letters every after 3 month and now my installment is R3,356.60. is there anyway I can get help by the looks when 2021 come I'll be doubling the payment"