I said it earlier, and I'll say it again. I think you need to abandon the white whale of a rebuilt engine in your original X and demand that they just give you a check for a new (used) one. THEY are the ones that have created the headache of an otherwise perfectly good X5 without an engine. You need to be able to move on completely and leave this problem squarely in the laps of those who caused it. I think you've gotten to the point where everyone involved knows that you're an exceedingly patient person, and they are absolutely exploiting that patience.

If I were you, I would give them a specific deadline by which they need to give you a check sufficient to cover the purchase of an equivalent X (plus any associated costs like shipping). If they don't provide the money by that date, then be prepared to actually file suit (small claims or otherwise) the next day. Piddling around with fly-by-night salvage yards/shops that promise one thing then deliver another hasn't gotten you anywhere, and I wouldn't be comfortable with that sort of resolution long-term even if they had come through.

__________________

-"Wax on, right hand. Wax off, left hand. Wax on, wax off. Breathe in through nose, out of mouth. Wax on, wax off. Don't forget to breathe, very important." -Kesuke Miyagi