|So then, you have the hard drive back in your possession? |
"However, I have arranged for an expert to have a look at it and am going to see him this morning". Experts come with verying skill sets. Just because the expert you used couldn't, or didn't, recover any files doesn't mean they can't be recovered.
If you have data that you really would like to recover if possible then post back and I can suggest some methods you can try.
BTW, the hard drive may still be under warranty.