where are you from?
changing the vanos seals and making sure all is good is quite easy, just time consuming.
more than likely the issue as they are known to have seal perish due to the buna used for the seals.
you can get kits to replace seals for about £30, i did my 330ci recently, took about 4 hours all in all taking my time. the alternative is getting a rebuilt unit, but they are significantly more.
is it single or twin vanos? i don;t know which models have what, either way it;s a simple fix if not a catastrophic failure.
commonly the idle is all over the place nearly stalling etc.