This sounds very familiar. I purchased a 2004 760i from Texas Truck Source in Houston in late October 2012. Within 25 miles of driving the care I had similar issues. You can read my post about HPFP failure and the expenses I incurred. Bottom line, I spoke with several BMW independent service shops and all recommended replacing both HPFPs at the same time. I did that and also ended with an entirely new fuel delivery system as the HPFPs were just one of the issues.
Also, Texas has a law on its books, the Deceptive Trade Practice Act. I consulted legal counsel about my issue and they receommended a thorough review of the DTPA and notifying the dealer with a certified letter an Intent to File law suit.