I completed all of the collectibles but yet I didn't reap the rewards

I have 100%'ed the entire game including March's add on, with the F1 and the Aston Martin. 6/6 Contracts completed on both vehicles. After 3 staring my last drift activity, I unlocked the Pista, that's it. I've done several High heat races, being at the required heat level also, to see if this "bug" will glitch me my items,, and I only now ever receive a volatile part but Unfortunately it's the screw supercharger, over and over again. Pretty disappointing seeing to only want to grind the game for the final colors and horn, and you only get a car. Yet the RSR can whoop this car, Lol. This game is GREAT without the bugs. I'd say the best one if you added back in the additional features like seen in Need for speed 2 Underground. Maybe even a lowrider, hydraulics competition event or gathering. But the nitrous purge for sure!