Hi, on a sim only pay monthly contract with three but my moto g2 is now getting too slow to use properly so I've decided to buy a oneplus 3. I've read on here and elsewhere that you can just walk into a three store and ask them to swap the sim for you (it would be micro to nano). My question is what would I need to bring? Do I need to bring my moto g2 sim or can they just do it in the store without it and I can just pop the new sim into my oneplus 3 when I get home and my old sim would just die? Thanks for any help.