HELP - Water ingress resulting in mould

[Thatsnotme]

This is the spare car within the household and tends to be driven a few times a week, unfortunately around a month ago we noticed that the windows were steaming up (when the car wasn't being driven) and that the boot mat was damp. We ignored the issue for a while but now its got to the point that it needs sorting, the car was not driven for around a week and mould has appeared across the rear and back side of the front seats.

I think the water is entering via the boot as below the boot mat there is condensation around the spare wheel.

What should I do? Has anyone else had this issue? How did you solve it? Of course the car will need a thorough clean once the issue has been resolved 

[RocketRossUK]

it will more that likely be leaking through the rear door seal or the boot seals. Go around every seal and make sure they are sat correctly. One small gap and you will get a ton of moister in the car. you can also go around and fluff you seals by lifting them up, squeezing them and back forth and re-seat them in position.

[Gtiless]

There was an issue with the pipe for the rear window washer breaking and leaking,its not that is it?

[Thatsnotme]

it will more that likely be leaking through the rear door seal or the boot seals. Go around every seal and make sure they are sat correctly. One small gap and you will get a ton of moister in the car. you can also go around and fluff you seals by lifting them up, squeezing them and back forth and re-seat them in position.

Have gone over all the seals once again and they all appear to be fine, unless I'm missing something.

There was an issue with the pipe for the rear window washer breaking and leaking,its not that is it?

How would I know if thats the issue, is there some way to check? Sorry I only have a basic knowledge of cars  Thanks for bringing that to my attention especially if its a known issue, will have a look through the forum and try find the thread regarding it