Fujitsu not replacing the defective tablet PC

bought a Fujitsu tablet PC one year before paying top dollars(About $2200). Instead of buying a cheaper model from some other manufacturer, the reason I bought an expensive fujitsu tablet pc is mainly because they were advertising everywhere that "Taking tablet pc reliability to the end o earth and beyond" in their website. But within three months its audio system stopped working. I requested them to replace the tablet PC as it was just 3 months and I believed it has a manufacturing defect. They told they will try to repair it first. On insistence, they told if I send the Unit they will probabily try to replace it. But when I actually sent it, even though they had to change the whole motherboard, it was not replaced rather they send back me the old one after repair. Thinking that it will work good from now on, since I didnt want to spend too much time on forcing them to replace the unit, I went on to work with it.

Now after 9 more months it has again developed the similar issue. This time the audio speakers stopped working. Now also when I am calling them and asking to replace it they are forcing me to get it repaired instead of replacing them. I believe that this unit is defective right from manufacturing and should not have come out of QA. So I would like this system to be replaced.

Please help me to get my tablet pc replaced.