Double debited tax free account

I have a tax free saving account with Nedbank with a stop order of R1500. I was debited on the 2nd of May with " Ref:S-O PAYMNT ********** ********** 180331 and to my surprise I received an sms this morning overnight transaction 03 May 02:07 Ref: S-O PAYMNT ********** ********** 180430 R1500 . On the money app this transaction does not reflect and the call centre said they can only see the on the 02 of May. They said they would transfer me to the sms department but were experiencing high call volumes. I would like this matter to be resolved ASAP.