Cafin asking for more money at end of loan Term

I took a loan with Capfin 2 years ago. Then at the beginning of last year 2014 I had financial problems i could not pay the account for 2/3 months or so (between Feb and April). I received a call advising me of my account being in arrears, I then made an arrangement to pay, and specifically told them to DOUBLE debit my account to make sure that my account is up to date, they did as per we agreed until I was up to date then my instalment went back to normal. So last month (June) I reached end of the term, after the last instalment they started harassing me with phone calls demanding more money, telling me that my account is in arrears. I disputed the amount because no one said to me there will be more money i'll need to pay at the end of the term when i made an arrangement with them. My question to them is why I was never informed of such when I made an arrangement with them, the agent said the amount is only calculated at the end of the term. I then spoke to the supervisor she then said a total different thing, she said the agent was suppose to tell me about this amount during the arrangement. They are refusing to write this amount off. Please help.