Hi
We also had this problem last year, and was told by the guy that fitted our aircon that it was a pre-installation problem with pipes behind the wall as they weren't connected properly so water was not draining away as it should. At the time we were lucky to get PW out to fix it, and to be fair to them they did a great job.
However, this summer we have the same problem in one of the bedrooms. This time it's proving a damn site more difficult to get PW to sort the problem. I would suggest e-mailing them at http://www.polarisworld.com/polarisworld/en/atencioncliente and hopefully they will get back to you. If this doesn't work then a trip to their head office might be needed if you are out any time soon.
Hope this helps.
Cheers
Simon