When such promotion as black friday is active, you see what you subscribe for and also see the rewards for the subscription you choose. We always state that by subscribing to premium (whenever the promotion runs) you can get maximum up to +1 month for free, and it’s true.
As for your dates related confusion, let’s see. I double checked to see that you subscribed on November the 26th on 23:07 (UTC). Your 30-Day subscription ran out on December the 26th 23:07, that’s when your reward became active and prolonged your subscription up to December 29th 23:07. Everything seems correct to me.
This makes me cry 
Our emails rock 
Check out this thread [Survey] Emails from VHTV ✉