Apple India — iphone repair

I own iphone 6s and its camera simply stopped working on its own. When i went to dehradun apple care, they told me that the replacement will take 4-5 days and i will have to leave the phone with them. However, when i ask them to give me the replacement for 4-5 days, they said they dont have any. I couldnt get the camera replaced that day, because phone is so vital in today's time. Please look into this issue and help me arrange a replacement if possible, so that i can get my phone repaired.