VAT registration needs two proofs of address, not one:
The registered representative's home address — proof in their name, no older than 3 months.
The business address — proof in the company's name, no older than 3 months.
Both follow the same rules on which documents SARS accepts and how recent they must be. See what documents SARS accepts as proof of address for the full list, and what to do if you can't get proof in the right name if the address isn't in your or the company's name.