Prorate charges from user when upgrade/downgrade subscription

[Test28]

Lets suppose,

1. My client have subscription plan of PayPal of $20/month and now he/she wanted to upgrade plan to $200/month on mid of the month.
2. My client have subscription plan of PayPal of $20/month and now he/she wanted to upgrade plan to $250/6-month on mid of the month.

In both cases, I have to cancel first existing plan and need to subscribe again to client with new plan.

Does PayPal supports take that amount from client?

1. My client have subscription plan of PayPal of $200/month and now he/she wanted to downgrade plan to $20/month on mid of the month.
2. My client have subscription plan of PayPal of $250/6-month and now he/she wanted to downgrade plan to $20/month on mid of the month.

In both cases, I have to cancel first existing plan and need to subscribe again to client with new plan.

Does PayPal supports differentiating amount to give back to user?