The car was advertised and confirmed by citroen as having disc brakes all round only to be supplied with drum rear brakes. Citroen's attitude was tough even though they confirmed the spec. They can alter it at will, without informing anyone.
Don't BUY a Citroen until you actually see the vehicle you want and CHECK THE SPEC>
Ifou read the small print of any motor manufacturer's promotional literature, you will find something along the lines of "we reserve the right to change specifications without notice."