Tax return

I submitted my tax return in August 2020 via efiling with all supporting documentation. Their system calculated that I would receive money back due to additional medical expenses I had to pay cash. On the 14th of Sept I received a notice of assessment with changes. The amount displayed was R1757 less than the initial calculation. The problem is, I received the R1757 and not the correct amount displayed on the system. Was the assessment done accurately?