PAYE payable calculation differences

I would like to find out the PAYE payable on a person receiving R16636. 60 monthly, no pension fund or any other deduction except SDL, UIF and PAYE. This person is 74 years of age, turning 75 in November 2015. I calculated the amount to R1390. 87 but the system calculates it as R1067. 11. I cant seem to figure out why the calculation result differs. For the 2016 tax year.

The monthly tax would be R1,185.34 as the person would qualify for the tertiary rebate as well given they would be 75 on the last day of the 2015/2016 year of assessment.

I don't know how the R1,067 has been calculated. Hopefully there is system support helpdesk you can contact to enquire how the PAYE is calculated.