out of warranty

i have a cellphone contract which ended on end of September, i sent my phone in for repair before the end of September thinking that it is under warranty because my contract had not ended yet. i now get a call to say it is in fact out of warranty because it is calculated from the day it was first used, which is two months before your new contract starts....why does no one inform you of this, i think that this should definetly be brought to the customers attention once the new phone is despatched. now i cant have my old phone repaired because i wanted my son to use it.