The Reserve Bank of Zimbabwe on Monday stopped operators of mobile-money services, the dominant way in which money is moved in the country, from paying out cash. It also tightened the spread at which dealers and bureaux de change can exchange the Zimbabwe dollar to between 3% and 5% from the official rate, down from a 7% spread imposed less than two weeks ago. On September 28 it banned the quoting of prices in foreign currency. Ecocash, a mobile-money service operated by Econet Wireless Zimbabwe, has 6.7 million active users in a nation of about 14 million people. It’s the first time since its introduction in 2011 that its users haven’t been able to use the so-called cash-back service. Econet is studying the directive and won’t comment on it yet, spokesman Fungayi Mandiveyi said by text message.