Apple couldn't replicate my problem during repair, what can I do?

Hi,

About two weeks ago, my macbook air bought in october 2012 (recently) suddenly wouldn't boot at all in the morning (despite working fine in the evening and being charged during the night.) I brought it in for repairs, and about 5 days later I got it back. After having used it for a couple of hours the same evening I got it back, the screen would suddenly go blank or lose its backlight, or the power would go off altogether (I guess, since the caps lock-light also turned off.) I brought it back to the apple store the next day.

A couple of days later, I got a call from an apple employee asking for further details about what triggered the issue so I told them as much as I remembered, and the day after I got another call from an employee stating that they couldn't replicate the issue. He thus wondered if I wanted it back as it was, or if they should send it back to service once more. As I didn't want my computer back if they had done nothing to it at all (except failing to replicate the issue), I told him that I wanted it sent back to service. He told me there wasn't much chance that they would be able to replicate the issue. Now it's been 6 days and today was when the Apple employee expected it to return from service. I haven't got a call from them.

I am going to call them soon if I don't hear from them, but I would greatly appreciate some advice of what to do in case they have failed to replicate the issue once more (and thus haven't fixed the computer at all). I have been very stressed out about this business both because I am studying my fourth year at college (computer science major) and I need to finish a programming project in less than two weeks, and also because the $1500 I spent on the Macbook Air (I got upgraded ram and processor) is a lot of money for me as a student. I dread getting it back and then getting the same errors as before when I am programming my project. Is it really up to me to be able to replicate the issue?

I currently live in California (which is where I ordered the computer from Apples website), in case it makes any difference.

Any advice is welcome.