New t-mobile phone and service plan

Hi, I was planning on getting a new t-mobile phone with a service plan
through Amazon and cancelling my existing t-mobile line. However,
Amazon has a statement on their rebate that voids the rebate if a new
customer cancels an existing t-mobile line before or after the new
signup. Would anyone know how I could get around this rule besides
having someone else sign up for the new line? Would appreciate any
thoughts. Thanks.