What's the best method to contact Delta with a complaint? I usually just use the form on the webpage (for positives and negatives), but I'd like to go a step further. If it helps, I'm a Diamond, and because I'm mostly on business travel, a pretty good revenue passenger. Mostly, this has to do with the (terrible) upgrade certificates. I've always had pretty good luck using them (about 200K miles a year) as long as I am not trying on anything involving KLM, but completely running into trouble this time (through NRT). Thanks for any suggestions!