My Wife had a 320D as a company car (53 reg) and the turbo did the self same thing at 10mph while I was driving it. It had only done 30k we were lucky that A) it was a company car and B) it was still under warranty, but the dealer who fixed it said if we were paying it would have cost over £5,000-00 just for the engine. The dealer did mention that it was not an uncommon fault!! Their way of saying it happens all the time. Taking this into account I took a full warranty on my 04 reg 320D Sport which I brought in May this year. Sorry to be the bearer of bad news but if you don't have a warranty to cover it it is going to cost you a shed load of money. You could try a re-con engine or transplanting one from a body right off? Good luck