Routine theft of guest belongings?

I stayed in the Sun City hotel, had a swim and put the damp (very expensive) costume and towel on the balcony of my 5th floor room. House keeping came in to separate the beds (after 3 requests!) and stole the items. (There was no way anyone without access to the room could have got access).

I reported it to reception and Client Service Manager (both twice). No one followed up. Security never contacted me despite being called in my presence.

I left my business card when I left and was assured someone would call me. No one did. As far as I could see this incidence did not even get recorded by Security as no one took down the details.

I assume theft like this is common place at the hotel and thus management does not follow up.