Unsuccessful warranty repair

Jumblebumble

DiddyDavies said:

Car_54 said:

True, but in the OP's own words it has "developed" the fault. I think any inherent fault would have manifested itself earlier, unless the OP doesn't go out in the rain.

An inherent fault could easily manifest itself many years after manufacture. It could something as simple as metal not being correctly treated for corrosion protection and after a few years it's rusted a bit and a small hole has appeared and this is where the water is coming from.
If it's a sunroof issue, it could be a shrunken or degraded seal, again, something that you would normally expect to last more than 3 years.

One possibility if it does have a sunroof.
Some cars with sunroofs have drains that run from them down a door or window pillar and one of these could be blocked or detached.
I used to have Volvo that had such a setup and the drain ran down the right hand windscreen pillar. Near the bottom, there was a spring loaded valve and the pipe became detached from this which caused the footwell to flood in heavy rain.

Citroen BX had a similar problem
The drain pipes came down the back and you had to remove the rear lights and then find the pipe which was not visible
This led to  quick  but  lucrative repairs by Citroen specialists