I bought an iPhone 5s 16 gb (AT&T) using an upgrade and cross upgrading on my moms account. i got it at a store other than apple and I want to exchange it for the 32gb. They don't have the 32gb in stock so I was wondering what is the process to return the phone and getting one at a different store still using the upgrade. Like how long does a reverse upgrade take? Will I need my moms old phone(before she upgraded) to out her number back on it? Will I need her iPhone 5(the one I gave her) to bring to the store to put my number back on it? (Then ill upgrade my moms phone and cross upgrade again) Sorry if this is confusing. Trying to write out what's in my head.