[Hoddi]

Hi all
i am a new bmw owner and recently purchased a used bmw e90 318i
i have a few issues that i was hoping you guys could assist me with

first the passenger front door leaks water, i´ve isolated the leak and the water leakage is somewere near the mirror and leaks into the carpets.
any ideas what could cause this and if it´s not a major repair how i could fix it myself ?

also the car is almost at 50.000km mark and the computer is telling me to have it serviced, i am trying to find out how much the 50.000 km service will cost and what it normally involves.

i´ve had bad luck with it, only had it a couple of months and
it has had both the front brake dishes replaced
also there was a faulty wheel bearing wich fell under warranty
and then there is the leaking door wich i am hoping i can fix myself to safe me some money (: