Intellicell Debited me for contract that i Finished paying

I took a contract with this company two years ago and the last debit date was last month April. They called and asked me to upgrade and I said no Thank you. Today they debited an amount of R301.65 in my account and when I call them they told me that they have made a mistake and they will reverse maybe within 7 working days but they can not give me a time frame. I told them how much of an inconvenience that this is for me and the lady in accounts told me its "Not their fault" like really whos fault is it because am not upgraded and the are the ones who decided to debit in my account. The consultants are very rude this is not the first time I am having alterations with this call centers consultants. An by the way the lady from accounts(Carlee) refused to give me an email address and dropped the line on me.