Books about Twinloss No 8 "Bang, Bang, you're dead" by Narinder Dhami

This book is an atrocity! I startet perusing through the German version in a bookstore and then found out I could purchase it via amazon.de for 0,01 Eurocent (+ E 3,00 shipping from the UK). So, I did read it, eventually, and was livid afterwards.
I have read other books by the same author and liked them. They were all about indian girls in british society and they were fun, but this one isn't nor is is designed to be.
The plot: Mia is fourteen an telling her story. That her twin brother Jamie is dead she mentions almost first thing on page one. She then proceeds to tell about how she and Jamie and their mother who has bi-polar disorder try to make it through life together. How her beloved grandfather died some years ago after shouldering most of the responsibility of the small family (the twin's father vanished before their birth). How her mother's behaviour becomes more and more unpredictable and bizarre and how Jamie threatens "to do something" and that he "may no longer be there" soon. So, when the rumour runs through school that someone with a gun is in the building, Mia believes it may be Jamie driven to something desperate and she sets out own her own to find him.
She tracks the shooter through the building rather smartly, finds out is is NOT Jamie, manages to lock him into a room, gets rescued just in time, ends up in hospital and when she frantically asks for Jamie meets the astonished gaze of a doctor asking her "Who is Jamie?".
At this point the intelligent reader realizes that Jamie as a figure has remained a bit vague, and for good reason: he died at the twin's birth.
The rest of the story is unraveled at high speed level. Mia sees a psychologist, tells her she has always known Jamie is a ghost. The shrink doesn't believe her. It takes Mia only two more pages to realize that she has made up Jamie herself, that she is even more bi-polar than her mother and has to have therapy. Knowing this truth about herself, she curls up in her bed, whispers "Good-bye, Jamie, I don't need you any more" and finita la comedia!
Thus Narinder Dhami turns the whole subject of twinloss at birth into an illness that can be cured, and in a jiffy!
I tried to contact the author and give her a piece of my mind, but her contact form would bounce back my emails and I couldn't find any other address on the web.
So, if you like a criminal story with a surprising end - or, since this isn't a surprise to you any more, know someone you might like to give it to - go ahead, but as far as twinloss is concerned it is worthless and possibly damaging.