Not what I expected

I recently bought all new appliances at a Whirlpool dealer, and was assured that this was a dishwasher that worked well in our area. Especially important to me was that it was an energy star rated product. I have used it now three times. The manual tells you to run your hot water for several minutes before you turn it on to make sure the water is hot enough. It also suggests that you turn your water heater up to maximum (not very energy efficient). Even with running the hot water first, it took longer than 3 hours to run through a normal cycle. The last time I used the light cycle and canceled it after 2 hours, it never did finish on it's own. I've since researched it on the energy star website and found that it only meets the minimum requirement for an energy star product, and then only if the soil sensor doesn't cause the machine to run longer than the minimum normal cycle should take, which is 90 minutes. The dealer told me that our hard water would cause it to cycle longer, and the manual tells you that softened water will cause it to cycle longer. Same reason given for streaks on my glassware. I've requested an exchange to the DU850 model which runs on the old dial timer system, and gets better energy star ratings. Whirlpool will not authorize an exchange because the machine is doing what is within their operating guidelines, and the dealer has told me that without Whirlpool's authorization they won't help me either. I now have a $400 decorative feature in my kitchen to look at while I hand wash my dishes.