Hi. I applied for myLifestyle plan 999 Iphone 16gb and was approved on Oct 9. Your representative called me yesterday confirming that my handset will be delivered on the 15th. Now I'm thinking of upgrading my handset to 64gb and I'll just pay the 24k cashout instead of 18k for the 16gb. Is it still possible for me to change it? What do I have to do?