There has been an unexpected turn of events in the battle of the billionaires, with Bollore’s Vivendi initially securing a 3% stake in Berlusconi’s Mediaset at the start of this week – a figure which swiftly soared to 20% within 48 hours. This has all the makings of a deal in which Vivendi will likely commence proceedings for a full takeover in traditionally aggressive fashion, perhaps even by the time this goes to press. Berlusconi and his family conglomerate Fininvest are clearly on the ropes and have since taken defensive steps. The long and short of it is that Mediaset thought it could try to rattle the cage of French mass media firm Vivendi with legal action, following the well-publicized…