If you haven't received the car then you should be able to get your money back but in fairness to the dealer, finding a fault in the MoT test and rectifying it for you before you take delivery is good practice. It's difficult to elaborate further without knowing what the part is, but if it has had to be ordered from the factory rather than central dealer stock it could take 2-3 weeks to arrive. I would ask the dealer what the fault is and maybe approach a couple of Peugeot dealers to see if they hold the part in stock. If it's an "order only" part then a nine-day wait isn't unreasonable if the dealer wants to rectify the fault before handing the car to you. However, if you need a car sooner you are within your rights to ask for your money back and buy one elsewhere.