My Vaio Pro 13, broke for the second time, help.

Hi everyone, first post here.
I bought a Vaio Pro 13" about 3 months ago, in the Sony.de website. Made the online buy in the 1st on August, and received the laptop in the 15th of August, in the 13th of September I was sending my first e-mail to Sony to request a repair. The service was horrible, it took ages to get it repaire and back to me, 3 and a half weeks to be more precise. And now again, it broke once more, same exact problem, it doesn't start, pressing the power button does nothing, the first time the motherboard was replaced, i suspect this is the problem again. By the way the first time the repair screwed up, my keyboard back light didn't work anymore after comming from repair.
What should i do now, i don't want this laptop anymore, i want my money back, can i ask Sony for that? After a week trying to contact Sony about this, the only thing i got was an e-mail aéreas on were to send my complain to.

Thanks.