Nope nope nope - this is way off base. Tax brackets start at about R180k/year:

https://www.sars.gov.za/tax-rates/income-tax/rates-of-tax-for-individuals/

If you're earning between R15 - R25k a month, you should be paying anywhere from R1800 - R3500 per month in tax, so I would suggest you resolve this ASAP, because you're going to end up with a lump sum owing of about R36,000 at the end of the financial year.

Use the Tax Tim calculator (https://www.taxtim.com/za/calculators/income-tax?)) to work out how much you owe, and if you're paying provisional tax (i.e. your employer does not pay PAYE), you should be putting aside at least R3k per month into a savings account for when SARS comes knocking.

You could even just pay Tax Tim to sort out your tax for you, it's like R500 / year.