MacBook random shutdown not solved... yet after years!!

I have been for almost a year trying to solve a problem with my MacBook unibody A1342. The classic 'random shutdown' problem. First, in the MacOnline store @ Viña del Mar, Chile, where I bought it, they said I have to send it to a service office in Santiago (150km far). They changed the power cord. They never saw the random shutdown problem and obviously I still have the same problem. Have changed the power cord again, three months later (guarantee expired)... and searching since then (a year ago) for a solution.

For a service review, now MacOnline store charges me CLP$49000 (about US$100 dollars) only for diagnostic.... Obviously until I have a minimal hope for a solution, I won't give up that hundred bugs... to wait for them to say 'no solution'

Is there a real solution for this massive problem with this **** MacBook???

There is a way that this piece of plastic & aluminium worth the US$1400 that I spent on it? The only Apple product I have, and this crappy!!!??? There is some hope?

angered to ****...