Please Refund My Money Back

I settled my loan a week ago, they sent me an SMS after a week informing me of the next debit order. I called them to let them know that I settled the account and proof of payment was received, they said its a system error, now they debited my account with an amount extra than my previous debited orders, I sent them emails to refund me, no answer, I called them and the first consultant I spoke to said it will be paid back to my account within 24hrs and it wasn't, I called back several times and I was given different reasons and the consultants kept on hanging up the call when I mentioned that they must provide me with their complains process before I approach the Ombudsman. Till today I haven't received any feedback from them.