My 3g just died on me (internal ear piece stopped working) and Apple won't replace because they say my phone has water damage (BS). Anyway, I'm eligible for an upgrade next month. Could I get the iphone 3g S by adding a line Friday and then cancel the line within the 30 day window? I know I'm suppose to return the phone, but could the store process the iphone 3g S as my upgrade on the main line when I cancel the other line?