Brazilian operator Oi has filed for bankruptcy, the largest such failure in the country’s history. The fourth largest MNO failed to win shareholder support for its plan to restructure $19.3bn of debt, as its country suffers a recession which has claimed a large number of company scalps. However, it hopes to continue offering services as it works out its future, which may involve prolific telecoms investor Naguib Sawiris. The Egyptian multimillionaire said he would be willing to inject money into Oi though some local analysts believe Oi will be broken up in a fire sale. Oi – and the whole Brazilian telecoms market – has been through a chaotic few years. Marco Schroeder became Oi’s sixth CEO in five years…