when i call them, they say got to buy the wipers at $29. and the most funny thing is , they suspect i bought a different wiper from wat is in their stock. It is the most ridiculous thing i ever heard.. i mean, wipers is wipers, wat diff does it make ? if they wanna make money, just say so.. no need to make such a lame excuse or reason.
anyway i have found out from my friends, is might be due to me using the normal window cleaner to clean my windscreen, and that is why the problem of jerkiness happens. Will try to clean up using water this afternoon, and see how..