Will try to cut a long story short.... Have a 2007, 335d M Sport touring. Recently had a brake fluid service at Sytner Chigwell plus their '2012 health check' offer for 20 pound 12 pence, they noticed an oil leak under the gearbox sump pan. They diagnosed this as a gearbox oil leak due to a warped pan and quoted me over 700 quid to replace the pan, refill the oil at 20 quid a litre (which apparently never needs to be replaced which i found out afterwards), cost to fit plus vat. I wanted a 2nd opinion so took it to a local Beemer indy specialist, put it up in the air and noticed straight away that it was an engine oil leak (black oil) and not gearbox oil (brown). Took them a few hours to find the leak as it was coming from the engine somewhere and running down onto the gearbox sump, hence it looked like a box issue. Eventually noticed oil coming out from the swirl flaps after having to remove the inlet manifold etc. Said it was a common fault and suggested to put blanking plates in place. Cleaned it all up, test drove a few miles and no more leaks. Cost me 280 quid. Would have been cheaper but it took them a while to find the cause of the leak, as the plates are only a tenner each and needed 6.
Never going to Sytner again and will certainly be sending them a sh1tty letter/email sometime very soon.
Recommend Highams Park Motor company in Chingford London E4, very good techs and seem very trustworthy.