Cablevision removed the BBC channel about 6 months ago. CNN International was zipped off as of April 1st. But not CNN in Spanish. It might be a simple matter of economics. It may no longer be cost effective to carry these channels. Cablevision is part of the Grupo Clarin now, as is Fibertel.
BBC; CNN and TV5 and some other channels are part now of Satelite TV. If you want to receive these and other channels you must pay an extra money 9,90$ PESOS per month and buy a device 99$pesos in order to be able to receive the signal by Sattelite. They have not dissapeared. Call Cablevision and ask.
These signals are now part of the "premium" package. Just like Cinecanal, HBO and others decided it was bad business to only have just one signal included in the basic package and created "Cinecanal 2" and "HBO2" (late 90's), where they included their best programming, thus turning the basic package to shite,