Do you have the same issue when you use your MacBook with other access points, like at a coffee shop with wifi?

If it works fine when connecting to other access points, it might be a compatibility issue with your access point.

If not, take it in to the nearest apple store and ask the Mac geniuses to take a look. You might want to schedule an appointment to meet with them. There's a link to set up an appointment at the Apple Retail web site mentioned above. They get busy, especially on weekends. This will hopefully ensure you won't be waiting.

You could also call Apple's technical support and go through some troubleshooting over the phone. Unlike other companies, Apple's support agents are actually quite good. You should not be on hold, the agent you'll speak to will likely be based in the US, and they generally know what they're doing.

Still though, there's only so much they can do over the phone, and this very possibly could be a hardware problem. If you take it in, troubleshooting should go a lot faster, and they could even be able to fix a hardware problem on the spot if it's simple. Plus, you could get some tips on working with OS X while you're at it.

Sorry to hear you're having problems with it, and I hope they get resolved fully and soon!