T-Mobile USA

Arrived into New York City yesterday night after flying in from Australia. Went to this T-Mobile store to get a new SIM card while I'm on my way rushing to a meeting. Noticed two guys in T-Mobile uniform at the front of the store smoking, no one else in store. One of them stopped and walked into store with me. When I asked for a prepaid SIM card, the guy recommended an unlimited SIM to me and said it will be $100 (not including taxes). I am a heavy user back in Australia and usually need an unlimited data plan because that's what I also have back home. Accepted it thinking it was a normal price and I will be able to claim it as work expenses anyway, I pulled out my phone (iPhone 5) and he said it will cost me $50 extra to change it so it becomes compatible, but thought just do it since I'm rushing and work will pay for it (thinking it but not saying it), at this point his mate has finished smoking and joined us in store. Then after the first guy inserted the SIM card, my phone just kept saying "No Service", then the other guys said, "oh it must be because your iPhone 5 was bought in Australia and won't work here", then he proceed to say he can fix it but it will cost $35. I felt a little suspicious then I explained I'm rushing and because it's not working with my phone I would like to cancel my purchase and get my money back. To which they say the SIM has already been activated and because of that I cannot get a refund. Then the second guy added he can get it done quickly and it will only be $10. I figured I have no choice and I need the phone for the day anyway so I asked if I will get a receipt to which they said yes. While the second guy proceeded to "fix" the problem I asked the first guy to give me my receipt, to which he said it will be sent to me via SMS. I explained that I cannot use a SMS receipt because I need it for work records but he persistently told me that this is not possible, after a while he picked up the phone and called someone (quite quickly I might add), who apparently said an email receipt will be sent to me. The guy then asked for my email which I then wrote on a post-it note. When I asked for the email receipt to be sent to my email now he said, it won't appear in my email inbox until about an hour later which I obviously won't be able to wait around for. Then I left the place feeling like I've been duped. Throughout the day my iPhone 5 could only get a 3G connection occasionally but more often it remains only an E connection. I finally got back to my hotel around 10 hours later and called T-Mobile and explained my situation which they agree seemed rather unusual but they are unable to assist me without a receipt. They have asked me to return to T-Mobile tomorrow and demand for a receipt. All I can say is I doubt they will issue me a receipt but I will try anyway. Wish me luck... I will update with my progress :(