Screen bleeding on Iphone 6s
i bought an Iphone 6s plus 3 days ago and after turning it on i noticed that it has some screen bleeding issue on the top edge of the phone, i went to the service in retail store and they told me that they will change it to a new one,but they said that they will only take the phone and not the box with it and it will take 5-10 days to ship a new one to me( just the phone) because they have to get it from Singapore. my question is that if i am going to get a new phone, why wouldn't they just give me a new phone from their stock and how can i know that the opened Iphone they are giving me after 5-10 days is new?
i payed a lot for that Iphone and i am not expecting to get a faulty phone and not being able to change it into a completely new one.
can anyone help me please?
iPhone 6s Plus, iOS 9.2