takingmoney without permission

Hi. I recently took a loan from absa online. It's suppose to be paid back over 36 month.they are charging me 24 months payments. I have tried repeatedly to have this resovled. No body return calls. Give inaccurate details concerning bank form.Can never get hold of Philip from collection.even tried twice going to the bank.only to be told they can't find my contract..have not put money in to my account. Now the debit orders aren't going thru.don't know what to do.please help