Incorrect debit order amount

On March 9th 2015 I entered into the DSTV Explora contract for R799pm. Since then it has been a constant struggle with Multichoice to get the correct amount debited from my account every month. On the 9th of March I asked that only my new Explora decoder must be insured and not my old decoder. My debit order should be R834 and not R869 what I am currently paying. I have made numerous calls to the call center and send emails to [Email Removed] On 3 June I received emailed response from Refilwe Makgobathe (case number ***) insuring me that the debit order amount will be rectified to R834. But two days ago on the 2 July 2015 the incorrect amount of R869 was debited again !