Terrible service on a new contract

I have opened up a contract in Jan and I'm already having issues with my D/O as now I will be double debited for April last months D/o wasn't put through and my date is the 25th of every month and the 25th was on a Monday last month.

I would like to cancel if this will persist as I haven't even had 6 months service yet and this has happened and I am highly disappointed in the service I have received and as well I am now unable to use my SIM which I had loaded data on as well making it practically different to do my job and verification takes place and that is the number i use.