I sent a complaint to Robert Webb (the CIO) about the slow internet speeds I consistently experience at Hilton properties. He responded the following morning and put me in contact with one of his direct reports responsible for overseeing that area. I was satisfied with the response I received and the communication.

Diamond Desk has almost always responded to my emails in a fairly timely manner. There was one time I sent a complaint about a stay at a property, and did not receive a timely response. I ended up sending the email 3 times and never received a response (even an automated one). I realized there was a chance the email was caught in a spam filter, possibly because of some of the language I used (I was complaining about the non-functional air conditioner in our room and stated I was 'sweating like a whore in church' - which I was). I ended up faxing the letter over and got an email from the property's GM within 1 hour. Again, that was resolved to my satisfaction.