Carrera Banshee not safe!

Had 5 carrera banshee mountain bikes all bought from halfords over a period of the last 8 years,the latest bike to have was bought in June 2011 by Nov 2012 the bike frame has compleatly snapped twice!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
They replaced the frame the first time, but refuse refund by the second time. There are defiantly much better bikes and suppliers you could go to and spend £ 700. Unfortunatly i learnt the hard way luckily i hadn't got around to attaching my Daughters child seat could have been a very different story!