Hello, Bathea -
This web page lists the South African Social Security Agency (SASSA) branch office locations:http://www.sassa.gov.za/index.php/85-contact-us
I am answering from the USA and see Sandton is located in Gauteng.
You will note the telephone number for the Gauteng branch office. I suggest you call that number to learn if there is any office you can visit which is closer to you.
In case you are unsure what sort of documentation you need to bring with you to apply for the Older Persons Grant (the current name of the Old Age Pension), see the information here:https://www.gov.za/services/social-benefits-retirement-and-old-age/old-age-pension
Note: Fixya.com is not the best website for asking questions about government grants in South Africa. Fixya.com is intended as a website for asking and answering questions on how to go about REPAIRING _THINGS_.
My suggestion for the future is for you to ask questions like this of a librarian at your local public library at
Nelson Mandela Square
West St & Rivonia Street
Telephone: 011 282 5911/5917
I am a librarian by profession