Waiter demanding 10% tip

O'Galitos centurion I was there on the 13th of March 2020, with my husband and my daughter. We paid for the bill and left R10.00 cash, just to say thank you for the waiter. The service went from good to BAD. The waiter insulted my husband by telling him that the R10.00 we left, will not even feed our daughter. I have sent an email to complain , I haven't heard anything from them. I will be going there today and I demand an apology for insulting my husband. The waiter is bad mannered because he even forced the people who were sitting behind us to pay 10% tip. He also told my husband that at O'Galitos you HAVE to pay 10% for the tip. There is a way of speaking to people and he was utter rude.