Account Paid twice

I had a contract phone which I took with MTN which was about to expire and I didn't want to continue with a contract so I asked them to keep my number as prepaid. The last debit order was supposed to go off on my account on the 02nd of March 2015. I received an sms from MTN at 06.43 a.m. on the 27th of Feb 15 advising me that my account will be debited for the amount of R865.40, then another sms was sent at 11.53 that my account is overdue I need to pay 865.40 at ABSA to avoid suspension. I didn't act on the second sms because I thought my account will be debited as per the first sms. I then tried to call 808 I couldn't go thru because my number was now a prepaid no longer contract. I called 173 three times on Saturday morning asking them if I should go pay or wait for this amount to be debited.I was then advised to go to a service center where I was told I must wait my account will be debited .On the 02nd of March received an sms saying that my outgoing calling facility has been suspended because I didn't pay. I then went to ABSA and paid the R865.40 to my surprise today I checked my bank statement MTN debited my acc so now it means I paid twice. I need my refund like yesterday.