I have water coming into my bedroom and cannot find the problem,

I have water running down my wall in my bedroom, the roof is not old but the window is, I did get a good named builder who said it was condensation!! However when it rains it pours in my bedroom, I don't know if I need a new window or lintel above my window, my husband is doing my head in cos even though he's not a builder insists its leaking some were. I have had a friend who does general repairs on his own property and he can't see any were the water would get in, I don't trust many tradesmen as they seem to just give lip service, take ur money and not fix the problem, help