The factory CD player in a Citroen Saxo doesn't have much in the way of options, particularly when compared to higher end vehicles. You can add these features and more by removing the stock deck and replacing it with a newer model with the options you prefer. This adds value to the vehicle, and may make it more attractive to a prospective buyer of the car.
Sit in the driver's seat. spread apart the DIN removal tools so that they each are in a "L" shape. Insert one tool in each hole located in the upper corners of the factory stereo, and push them in until they click in place.
Hold the tools with both hands, and pull them towards you while simultaneously putting pressure away from the centre of the stereo until the stereo pops free of the dashboard.
Slip the factory stereo out of the dashboard until it can't come out any further. Disconnect the wiring harness and antenna lead on the back of the deck using your hands, then remove the stereo from the car.
The DIN removal tools can be found at most car stereo shops, or even at the dealership. If you can't find them under the Citroen brand, you can use Ford or Mazda radio removal tools, too.