Cancel Backordered Phone order in order to buy different phone

Hello,

Ordered a phone on Sunday, agent did not mention anything about being backordered.  Got an email next day indicating phone is backorder for whole month.  Went back to store to switch to different phone that is available, but was told cannot switch.  I have to cancel first, but they said they cannot do it at store, have to call and cancel.  First agent cancelation email was sent to manager for approval.  Today, another agent stated order cannot be cancelled.  Getting runaround.  Very furstrated.