More than half of teenagers believe they have made the wrong choice of GCSEs and A levels, according to a survey published yesterday by ExamAid and the Association of Colleges. Nine per cent of students questioned said they would like to change all or most of their subjects. Another 46 per cent said they wanted to abandon some of their chosen courses. A third of teenagers believed that their courses would definitely help them to achieve their career ambitions, while 57 per cent expressed doubts.