I would still approach Lexus, you could argue that after having the clutch anf DMF replaced by them you would have expected not to be having problems again in such a short time and mileage, the components should have some warranty on them.
With the noisy release bearing you mention it makes you wonder if they fitted a complete 3 piece clutch kit or just the friction plate.
Have a go at them in a nice way, they may accept liability.
Ask them to test drive the car with the faults especially the foward jump when going into 1st and ask if that seems acceptable and safe for a car of such prestige,age and mileage.