Inaccurate billing of the loan

I had two loans with old mutual. One was for 3 years the other was for 5 years. The 3 year loan ended in roughly in February 2016. The 5 year loan was supposed to end this year February 2018. When I went to go check at the ghandi square branch, they checked on their system and it showed that I owed R2500 and something in January were I was informed of a refund, instead they charged me everything and to my surprise I wasn't refunded. February they charged me the R2962.56, when I asked why they didn't give me a straight answer just differnt stories. When they were supposed 2 refund me they said that I owe them R112. But they took the whole amount, they said that no refund is due to me, I said I supposed 2 finish in April but the system my loan will be done in February as they showed me at the branch that I don't owe anything, they left my budget with a dent due to there inaccurate billing, I want my refund and the inaccurate amounts that they were putting, I called the head office and the hear office isn't helping as they saw the amount outstanding and last payment date, I need my money as I have other accounts to pay.