From the FAQ I see these two answers: 1)How can I upgrade my phone by using the Tab? You can upgrade at any time by using whatever room you have left on your Tab, up to a maximum of 500. 2) Can I use my positive Tab balance when I upgrade? Yes; with all Tab options, you can use your positive Tab balance, as well as the full available negative balance of your Tab, towards a new phone. For example, if you have the maximum positive Tab balance of +150 and you qualify for Tab L, you have up to $650 to use towards a new phone! I'm so confused. One says I can use "whatever is left" and one says it's both "positive and negative" that I can use towards a new phone... HELP!