screen flicker

this screen flicker on my macbook is driving me insane. It makes my computer almost unusable. I took it to the apple store to get it fixed, and they were going to send it out to get fixed, but they were going to keep it for a week, and I need it next weekend for my dad's memorial service, and didn't really trust that they were only going to have it for a week, since it seems that generally people who have posted about problems of this kind as well as repairs have had reported that they got their computers back after about 3 weeks. As soon as I get back into town, it's heading right back to the shop.