My rear left side passenger door is leaking, monsoons have just started in India and they last for a good three to four months.

Water collects between the door gap and the rubber seal and when it gets too much it drains on to the carpet.

Can anyone suggest what the problem could be?

I own an Octavia 1.9 TDi, 2008 model. The dealer had told me its a door setting problem but after getting the same rectified by the dealer itself, the door still leaks.

Please advice

It is a well known fault with Octavia's, it will be the rear door carrier most likely and the foam seal that surrounds it lets water through eventually and into the car, and with the amount of rain you are about to expect this is best off sorted as soon as you can. There is a guide on here how to take the door card off and access the carrier. Good luck.