Has anyone made an official complaint. Fed up with email and no really response.
I have always had very good and fast responses when I've had issues with DLP but one time I was getting really frustrated with a problem that just wasn't getting sorted so I added "FAO: Philippe Gas" to the subject heading to show I meant business and got a speedy response ;)
These have only ever been things that I wanted to get sorted out though, e.g. when the website messed up my booking, rather than actual complaints. If it's something serious you'd like to complain about, maybe try giving them a call?
How long ago was it you emailed your complaint, and which email address did you email it to? Was it a complaint you requested a reply to, or was it more a general moan?
Try complaining about people smoking in queues, that never seems to get sorted :(
I made a complaint on our last trip (though this was a few years ago!) about quite a few issues with the hotel. They were very slow in replying (I emailed) but eventually did and offered us a free 2 nights/3 days stay as compensation! Definitely persist. You may not obviously get the same in response as us but they should get back to you eventually :)