customer downgrading and upgrading to packages

[nuksws_99]

Hi, we are having problems when giving compensation to users who have currently active subscription and want to upgrade to a new, more expensive package. We give equivalent free trial days if the user upgrades or downgrades for a new package. An example would clearly explain the problem.

Let's assume that we have 3 packages.

1- Free

2- 30$ Silver Package

3- 60$ Gold Package.

User buys 30$ silver package and used it for six days. Now, he wants to upgrade, but he has 25 days in silver package (24$). So, when he clicks to upgrade to gold package, he gets 12 days of free trial, at the end of which he will pay 60$. 

I think this flow is okay according to shopify documents.

However, here in our database we assume that user has paid for the golden package ( since we cannot check if we have received the payment or not ). Now, if the user downgrades into silver (30$) package, he gets 60 days of free trial, which is equivalent to 60 USD. As a result, user gets free 60 days after just one payment in the app.

Is there clear flow that I can follow for the apps that have monthly subscription packages?

Can i block user's ability to downgrade and upgrade for one month after users changes his package?

Can i disable downgrades and upgrades, if not, what can i do in this situation?