Vodacom Group [JSE:VOD] and MTN Group [JSE:MTN] shares fell after one of the competition regulators ruled that SA’s two largest mobile-phone companies overcharge customers for data – particularly those on lower incomes. Vodacom, majority owned by UK-based Vodafone Group, and MTN had a combined 75 million customers in South Africa at the end of 2018, or about three-quarters of the current market, which includes those with more than one mobile-phone subscription. Smaller carriers have long appealed to regulators to curb the dominance of the top two carriers, while the high cost of data has been the subject of street and social media protests using the hashtag #DataMustFall. Vodacom dropped as much as 4% in Johannesburg, the most in three months, while MTN fell by 2.9%. “Vodacom can confirm that, as part of its ongoing pricing transformation strategy to address the cost-to-communicate in South Africa, we have reduced the effective cost of data by 34% in the past calendar year alone,” spokesman Byron Kennedy said in an emailed response to questions. One reason is the government’s repeated delays in providing new mobile spectrum, which would increase access and bring down costs, it said. However, any upcoming auction should be based on a requirement for providers to cut fees and lay on services including free WiFi in public spaces. The wireless carriers’ views on the findings should be submitted by June 14, while a final report will be published later this year.