A few months back I had need to complain about a few issues in my room (cleanliness and maintenance). As there were several things, reception asked me to put it on an email to their reception email address. However this went ignored - so I sent an email to the same address the following night to chase up and was again ignored.

When I completed the guest satisfaction survey that comes through a few days after my stay I made sure to describe my issues and that it was ignored by the hotel - and the next day central Honors customer service emailed me back to say they would add on 20000 points as compensation.

Perhaps the email survey is a good place to register your complaint.

The next time I stayed at that hotel I received noticeably superb service so perhaps they left a note on my account!