Communication when changing indefinite Subscription Plans

Hello,
I feel I've the Membership plugin set up and working exactly how I want it to be... well, almost.

I've got 2 subscription plans set up. 1. Pending & 2. Active.

When a user signs up to my site they go into the Pending plan which has no access to premium content until I approve their account by changing their plan to Active. The reason we have it set up this way is because this site and content is available for free to members of the association.

The problem I'm facing is that I need to be able to notify the user when their account is changed from Pending to Active. I've played with the Communication feature and it appears that this only emails the user when their subscription is about to expire or after it is paid.

I've tried both of these settings but haven't had a successful outcome with either. When I signed up a test account using "after a subscription is paid" and before I change the subscription of the user to Active I received an email saying my account is active.

Am I doing something wrong here? Is there a better way I can set it up?

Ideally, when a user signs up I've got the default email to them telling them that their account needs to be approved (which is working fine), then when I change their subscription manually to Active it needs to fire off another email telling them that it's now been approved and that they can access the premium content.

Really looking forward to your advice or any suggestions you have.

Many thanks,
Daniel.