to be fair, your specialist probably would have suggested flush if they thought it would work [ if they are honest ], BMW dont realy care because the amount of serious issues is small in the grand scheme of things and angry customers are just classed as acceptable losses, no different than other big buisness, doesn't do you any good though sadly. IMO BMW are amongst the small amount of excellent makes and if treated correctly from new they would prove that IE a gearbox run in service at around 1000 MILES/KM's, but they dont as they pander to the fleet buyers, usualy by the time issues arise the vehicle has passed to the next owner with either no warranty or a non BMW aftermarket warranty both of which works to the benefit of BMW, all the manufacturers work like this to a greater or lesser extent, it's just the Motor trade where the end user comes last and always will, it really means all new owners new or second hand need to be "on the ball" when it comes to their vehicles, but that would mean education so that will never happen 😉 i dont like gossip about vehicle faults though as they cause more Red Herrings than anything as major faults usualy are a tiny minority, i remember when Ford first started using single point fuel injection across their range, the public were used to Carburettors and pumping throttle pedals and as a result the new cars were flooding right left and center even though starting instructions stated dont touch the throttle while cranking, the gossip started and Ford were slagged off as never starting in the cold or wet, but the reality at the time was for every ford that didnt start 2000 always did...the negative news won as it always does, People [me included ] love to rant and rave and blame anyone and anything, it's just human nature, life is frustrating and cars realy realy dont help, we could all buy horses, but then some of us would end up being kicked in the nuts and the seller would get the blame for selling a dodgy horse