My advice would be to look back at your applications and identify points to improve. Make sure you clearly express why you want to pursue a career in commercial law rather than saying something that could be applied to investment banking, consulting and other sectors. Try to ask yourself whether you have a specific reason for joining the firm rather than "I want to join Firm X because it has 33838 offices and is rated Band 1 in Corporate". You need to go into specifics as to why the reason you chose appeals to you. With this try to make a link to your motivations and your past experiences. Finally, show recruiters the skills you have obtained and how these could be applied in a career in commercial law. If I remember well, Commercial Law Academy's "Writing successful applications" deals exactly with this type of content by looking at talking about your experiences and motivations for joining a specific firm.