incorrect debitorder

this is my third attempt at getting an answer about my account an amount of R898.00 was deducted again on the 29th of March 2016 here is a my first query \i am currently on DPP meant to be paying R799.00 per month on the 28th Jan 2016 an amount of R947.50 was deducted then on 29th of Feb 2016 an amount of R898.00 was deducted, i have called the call center numerous times and every time i get same response we will look into the matter and let you know outcome, the most annoying thing is self service says an amount of R799.00 was deducted but that does not reflect on my bank statement, all i need is an explanation as to why this is happening\" PLEASE CAN YOU EXPLAIN THIS MESS TO ME"