Amazon - I Have received the used

I have received the used phone.. first i have ordered the phone on amazon on *th may it is delivered on *th may. i have doubt on box because there are two barcode on the box and inside box accessories pack is teared . i have raised the complaint in amazon and they told to contact *days after and i contacted on **th may they told we can't replace/replace the product. amazon told that from our end everything is right so on may **th I visited they samsung official service store near my house. they have checked with IMEI number and told that this phone is activated on **th April how can it is possible i have the phone on *th may. amazon customer care is telling we can’t help you further. and they simply telling used the phone