DJT Rob

I have just bought a Xsara 2.0 diesel 2002 reg and love it. Problem is it dident come with a radio in it... I have fitted a pioneer I had but obviously no steering controls cause you have to buy a £35 adapter! Question is is that I want to buy an original unit for the car but I don't know which one I am suppose to buy as there are afew types!? Also I'm not so sure about the coding if anyone has a clue as it dident have a handbook! Any help appreciated!