NEED SUGGESTIONS!!!

OK, my sister did a wonderful thing and surprised me with a new cell phone, i had been toying with the idea of getting one, still didnt know what i wanted yet, or if i wanted to renew my contract. well she shows up at the house with a new phone for me. it made me happy and feel loved. the thing is. SPRINT gave her all my account information, renewed my contract for 2 years, AND gave her my discounted upgrade price... AND switched over the phones, all without my knowledge. now, my sister does not have the same last name as me, and really had no info other than my name and phone number. THIS worries me. How could they do all of this? im happy my sister thought of me, but she shouldnt have been able to go that far in my account without some authorization from me, so im pretty upset at sprint right now. im not sure if the phone is really what i wanted, i mean, i like it, and would probably keep it just cause its what my sister got for me, but im going to go in there tomarrow and raise hell a bit. i might be able to get a really expensive phone for all this. cause they TOTALLY violated every privacy act. anyone could have gone in there today with my name and number, said they were my brother or sister, bought phones on my account, added lines, whatever. i dont feel comfortable with that. im looking for feedback. i will always have a cell phone. so... should i ask for a nice high grade phone? or a couple months free on my bill? cause i am going to ask for something like that, or threaten to turn them in... i mean, there are some serious legal issues here.  i even have a copy of the reciept that my SISTER signed renewing my contract and all its details and authorizing the activation fee. that is not legal. she didnt know better really, she thought she was helping and trying to surprise me. so any suggestions on what i should ask for???