Yes, customers can upgrade or downgrade your plans from the Client Area
When customers place an upgrade or downgrade order, they will receive a credit what they haven't used of the current cycle on the existing plan and then charged for the remainder of the cycle at the new plan price. The next due date doesn't change.
Total Payable Today
Old Plan: Price Per Day * Number of days until next due date = Amount Credited
New Plan: Price Per Day * Number of days until next due date = Amount Debited
Total Payable Today = Amount Debited - Amount Credited
Semi-annual or Annual Plans
Clients will receive a credit on their account pro-rated when downgrading their plan.