Change of bank details can be done:in person at a SARS branch (During the pandemic, it would be best to make a telephonic appointment with SARS and then send them your supporting documents, SARS will contact you and do the update over the phone with you.) via eFiling (Go to Maintain ...
you can link cards from local banks or use virtual cards from services likeChipper CashorEversend. Linking a payment method is not mandatory for sending payments, but without adding a bank ATM card, you can not make your payments online, so adding a card is crucial if u want to be paying...