Payment & Price Issue

Hi, I’ve created 3 memberships as follows:

Premium ($100/mo)
Standard ($50/mo)
Free ($0/mo)

Now when I started testing, I created a Standard Member and made a payment of $50 and all was well. But right after that, I tried to upgrade the same member to a Premium Membership, but this time the plugin charged me the full $100. How does that work? What if this happens with real clients? If I change my mind within a few minutes, should I still be charged the ‘Full’ amount? Not the remainder of the amount I just spent on the Standard Membership? Is this a bug? This seems to be pretty basic! Any idea how to avoid that? The remainder should be charged if the upgrade is made within the same billing cycle, right?

Any idea how to fix this? Do you have a provision in the plugin? Or we need to go buy something else to handle this basic issue … Plz, let us know. Also, is there a way to look at just the tickets I opened? Not everybody else’s … thanx.