What happens if I unlock a new status before I have used all of the Personal Double Points Days I already had?

You will retain the remaining value of the benefit associated with the previously held status, but also note that this benefit is not cumulative as you progress through The Designs on Giving Club statuses. For example, if you are at a status where the maximum Personal Double Points Days is 2 days and you have used 1 day, when you progress to a status that provides for a maximum benefit of 3 days, you will have 2 days left to use.