Oger Telecom has rejected a R14 billion offer from Africa's largest fixed-line operator, Telkom SA, for its 75 percent stake in South African wireless carrier Cell C, according to a person familiar with the matter. Telkom is now conducting due diligence on whether to make a renewed offer for Dubai-based Oger's stake in South Africa's third-largest mobile-phone company, said the person, who asked not to be identified as the matter is private.