Citroen use 3 coloured bands on the springs to help identify them, can be a mix of green, blue, white, yellow, red. So if you clean up the old springs you should be able to use this to ensure you have the right one. Ideally you would use your vin on the Citroen parts site to get the correct part no. When one broke on our 2003 C3 the dealer replaced both so they were matched and just as well since it was not quite as before, seemed a little higher and handled a bit differently to start with. Provided you gave CES your car details they should have supplied the correct part and if not then I would expect them to take it back. The top photo definitely looks as if the spring is not seated right and off centre. Did it look like the old spring ? When you have a look, if not seated right it may be possible to use your spring compressors to compress it and reposition it without having to remove it. On the General Discussion section there is a link to Citroen parts prices and it looks as if a spring from Citroen is about £74.