horrible service

Good Day , i recently took out a contract with mtn and my first payment with Pro rata was due on the 30th ( last day of the month ) I downloaded the app while busy with the contract and was informed it will make my life easier . It did exactly that . I went on just after the 20th to check my billing which was not yet uploaded , contacted mtn via twitter and they said it should reflect month end , the request was then to keep the 1st instalment date as the 30th but going forward can they update to the 25th because i get paid on the 20th . Debi check request was sent and approved . Waited Waited and waited ... 1st instalment has not gone off? why? I do not want an overdue account in my name i demand that the instruction for a debit order be sent to my account today and that the instal due for month one be marked as successful . I will not be charged pro rata for 2 months . REF ***