can we pull something like the following together?

Dear {Full Name}, 
As we are coming to the close of Octave Opportunity Fund, we would like to give you the opportunity to 
1) Send in the remaining payment of $(Subscribed amount - Paid amount)
2) Update your subscription to $(Paid Amount) from the initial $(Subscribed amount)
3) Add to your initial of $(Subscription amount) and send in the full payment 

If we don't hear back from you in 5 business days, we will assume you want to keep your interest in Octave Opportunity Fund to $(Paid amount) only.

Regards, 
Admin OctaveHI