How to stop having paniac attacks in social situations?

Handbook of Self-Help Therapies, which reviews studies of books and programs, says that the writings of Dr Barbara Markway help people with moderate social anxiety. Her most recent book is Painfully Shy.

I can tell you something you can try, but I have a feeling that you should see a professional about your problem.

The kind of therapy used most often for phobias is exposure therapy - exposing the person to what's feared. Ideally, the way to do this is to start with something fairly easy and gradually progress to things that are more challenging. There's a type of exposure therapy that involves imagining what's feared. 

What you might do is get good and relaxed and imagine a social situation. At first, it could be something very easy, but in the following sessions you could make the situations you imagine more and more difficult.

Here's a really good way to get relaxed. 

Two psychiatrists, Brown and Gerbarg, say a 10 or 20 min slow breathing exercise - 5 breaths a min - is good and 20 min twice a day is a therapy for anxiety. The exercise is inhale and exhale gently, 6 seconds each.  

You can use breathing to calm down before a social situation and during one.