Whistling noise from window blower and bluetooth problems

I'd reckon that the whistling noise is air escaping out via that route, so, does that mean that you have accidentally blocked the vents in the boot area that should get blown open to let this incoming air displace some existing cabin air?

Edit:- it is well known that Ibiza allows rain water in the top of the door frame, which you might have noticed when opening the door after it has been standing parked while there had been rain. For what it is worse, Polo does not have this issue and I don't think that Fabia does either.