Was my case, called 611, was told that since I have a pending order for an iPhone 6 plus (don't forget the plus, lol), they couldn't change the plan until I get my new iPhone... (the iPhone is supposed to be here in the middle of November) so either cancel the iPhone order or hope that the new iPhone will arrive before Oct 31 which is the offer dateline...
I told them to hold their horses, that I was going to think about it...
So... I immediately called my friends at retentions and asked them what is going on... they apologized and told me that they can't change plans until I get my new iPhone... So they did the next best think... they credited $70 for my troubles, they are going to switch me to the 30GB plan at any time when I receive the new iPhone, from this moment on, any data overages between 15GB and 30GB will be covered by the retentions department...
That is exactly why. Thank you, I do have a phone waiting to get here.