Folks who pre-ordered an iPhone 4 from Radio Shack may still be feeling the sting of not getting an iPhone after a less-than-expected number of handsets were available. Radio Shack reached out to let us know that it is extending its iPhone 4 launch promotions for an additional month to make up for this disappointment. From now until July 25th, any customer purchasing an iPhone 4 will receive a $20 accessory credit and can participate in the Trade & Save promotion. Trade & Save allows you to trade in an iPhone 3G for a $100 credit or a 3GS for a $200 credit that can be used towards the purchase of an iPhone 4. Lastly, the Shack is also extending its promotional iPhone 4 accessory bundles that contain anything and everything you may need for your new handset. The best news of all, though, is the assurance from Radio Shack that its supply of the iPhone 4 will be replenished as early as this weekend and will continue to be replenished throughout the month of July.