My MacBook and my iPad were lock last week. I went to one authorized service center nearby and they said that all data will be lost. On top of that, I have to pay $50 per device to unlock and reactivate it. Then I called apple customer service, they filed my case. They couldn't do much for my MacBook and refer me to other authorized service center. And they said that they will call me back in 2 days for my ipad. I went to the service center as advised. They were able to unlock my devices in less than 2 hours. All the data in my MacBook are safe. They took out the hard disk (I have Mac Book Pro) and I keep the hard disk while they uncloked it. They replace the hard disk and my Mac Book is back to normal. For my iPad, it should be restored and all the data is gone. For this service, I needed to pay about $55. Although I have sort this problem with local service, the Apple service center still called me back to follow up my case. So, I appreciate that.
My advise if you have this problem with your Mac Book, go to local authorized service center and ask if they are able to unlock without restore your Mac. If they said it has to be restored, try to go to other service center. The technical guy who helped me to unlock my mac said that it was just about unlocking the Mac, nothing to do with your data.