Laptop worse after repair

My advise to anyone wanting to purchase an Apple computer, DONT. All Istores have the worst service possible and they couldnt care less!<br> <br> I own a fairly new Macbook Air (7months), I support Apple as it is a premium brand and only use Apple. My laptop just died and i took it in to the Fourways mall Istore branch, they booked it in for repairs. according to them it would only take up to 5 working days, it took 2 weeks! I collected my unit today, they did not even test the unit in store to see if i am satisfied with the repairs. Once i got home and switched on my laptop, it makes a horrible ticking sound! clearly something is loose inside as when you move the laptop around the ticking gets worse or disappears. <br> <br> I emailed the service centre explaining my problem, they now requested me to send it away once again! I feel this is absolutely unacceptable as they did not do their job properly and i would love to know how it passed quality control??? I feel my unit should be replaced as you pay a fortune for Apple products and clearly the technicians dont know how to do their job! It is still under warranty and i am not being unreasonable to ask for a replacement!