I've posted here on this subject before. I had the same problem from new on my GTD. Squeaking and juddering... Drove me absolutely nuts! I tried vinegar, I tried clay bars, I bought several expensive window cleaners/polishes, I tried RainX... I replaced the wiper blades twice! Nothing worked!
Then, for a completely unrelated issue, I had my windscreen replaced under warranty. My wipers have been blissfully silent ever since! I can only conclude that my original screen had some crap on it from the factory that just wouldn't budge. If the car is new, the wiper blades should be absolutely fine. I binned 2 perfectly good sets! Your problem, I am 99% sure, is the screen. You just need to find a way of cleaning it... Or more drastically, replace it.