But the watchdog said a reasonable consumer's most likely interpretation of the bank's ad was that data worth R149 would be credited to them and depleted at 7c/MB.
"It is also implied by the introductory idea that you will have a fixed cost," the watchdog said in its finding.
"In addition, consumers are currently familiar with advertisements by different service providers offering deals and plans in a form of subscription contracts with airtime, data or SMS bundles already included in the monthly subscription fee.
"They might, therefore ... understand this plan to be similar to those that they are familiar with."
The ruling said Standard Bank's "how it works" example "does not offer any clarity at all regarding the issues at hand". In fact, it strengthened the incorrect impression that the monthly fee was an airtime credit.