Someone needs to call me ASAP!

I paid extra in December on my 6 months interest free account. According to my statement in Jan, the installment stayed the same as the other months not taking into account the extra I had paid. I sent an email and enquired, I was told to ignore what's on the statement and given the amount to pay. Again for Jan, I paid extra... Now ive been sent a mail that I am in errears for R160. Please fix this! I cant be doing run arounds on stupid things like this.