Airport card on MacBook stops working when moved

Hi everyone, I've had this issue with my MacBook and I really don't know what to do anymore right now, so I hope someone here could give some advice.

Last week my Wifi stopped working properly. I noticed that nothing connected anymore, and then it turned out that the whole Wi-Fi dialogue became unresponsive. The list of networks didn't update, it was continuously scanning for networks, and in the network preferences, the Wi-Fi showed up as being off. Clicking the button to turn it back on didn't do anything (it wasn't greyed out, I could click on everything).

I came to the conclusion that this seemed to happen only when I moved the MacBook. The WiFi was fine when I just sat at my desk all day, but most of the time when I went to another room with it, this happened.

I was on the phone with Apple support for a few days. They suggested several things to test. We tested, we waited, I observed, we tested again, waited observed. Needless to say, the problem persisted. After a few days I was advised to reset my MacBook completely. So I did, waited observed, and it still happened.

I was then advised to go to the Apple store. I spoke to a Genius, he told me that the Bluetooth wasn't working and that it's probably the same issue. He told me they would replace the AirPort card and that would probably fix the issue. Several days later I got a call that this didn't fix the issue and that they would have to replace the logic board. At this point I had to keep telling the people from the Apple store what the actual problem was, which is that the WiFi stopped working after a while when I moved my MacBook sometimes. They kept reassuring me that it was the same as the Bluetooth and kept referring to the Bluetooth in all communication. I asked them to test the WiFi first, which they obviously didn't do, since they didn't know that was the issue, before I authorized replacing the logic board. They said ok and that they would call me before the store closes on the same day.

Well I didn't hear from them, and eventually after a few days when I called them to see what's happening with it, they told me they replaced the logic board and that it was all working. I picked it up, I went home, I used it for a couple of hours and then the WiFi thing happened again. So this is where I'm at right now.

So, where do I go from here?

I am really dependent on my MacBook atm, as I'm finishing up my PhD thesis. I'm also not rich, so I can't have all parts of my MacBook be replaced to see if anything ends up working. I figure I might as well buy a new one if that's the only possibility?

Every Apple employee I've been in contact with was really friendly, so I can't complain about that, but I feel like nobody is really looking at the actual issue that I'm having, so handing the MacBook in for repairs again really worries me (apart from the fact that it takes a lot of time that I shouldn't spend if nothing comes out of it).

Does anybody have some advice?