I need a trade (dont know which one) to fix leaky French doors

I have set of french doors (UPVC) which leak from the hinge causing damage to the floor and fights with my partner so i need to get this sorted. I suspect my neighbour downstairs has the same problem.
The sealing around the door looks fine and wonder if its coming from inside the wall cavity, in any case i need someone to give me their POV and a cost to fix it