Cannot reiterate this enough:
PLEASE don’t request refunds from Apple for any unused time on your Twitterrific or Tweetbot subscriptions.
It could literally bankrupt small shops like these.
Want to know when I post new content to my blog? It's a simple as registering for free to an RSS aggregator (Feedly, NewsBlur, Inoreader, …) and adding www.ff00aa.com to your feeds (or www.garoo.net if you want to subscribe to all my topics). We don't need newsletters, and we don't need Twitter; RSS still exists.