Cancellation of contract

On 28 December 2017 I contact the MTN and cancel the data contract of number ********** 327, the starting contract date was 2015/09/09, that means more than 24 months. I was informed that I should give one month notice. They informed me that the contract wast scheduled to stop on 28/01/2018. But an stop order for the full amount was still go through on my bank account on 1/02/2018. Can you please stop the stop order immediately and pay back amount that was over billed.