Renault Clio stop light and battery light flashing then on, then all lights on and loss of power

I was driving my clio the other day when the stop light and battery lights came on, to start with they just flashed then stayed on and whilst driving my other lights came on and i then lost all power in the car, once i stop the wouldn't start again completly dead. the RAC said that it was the alternator had failed but i have tried charging my battery and that wont even charge, so am guessing will need new battery, any help really well come
Thanks