I subscribe to Dish America. I don't get the Platinum channels either. Dish Network's web page explicitly states that you get Platinum with "ANY HD PACKAGE". However, customer service and the CEO office both have told me that this is incorrect but no one has done anything to fix the website either.
So I've filed a better business bureau complaint asking that Dish either provide Platinum HD with Dish America, or that they fix their website to state correctly that Platinum is not included with Dish America. I haven't heard back yet from BBB or Dish, but I'll make sure to post when I do hear back.
ps... I'm already 99.9% sure that Dish Network's response will be that they will be happy to 'upgrade' me from Dish America to the Top 120 package with HD and Platinum at the price of Dish America. However, that isn't what I want. I want them to be offering honest advertising -- not appeasing me as one customer.