Can I inform DVLA that I have sold my car via phone?
You can call DVLA at the number - 0300 790 6802 for any vehicle related inquiries including advice on how to change ownership. However, you can not make the change via phone or online. You will have to fill the right section on your V5C form and send it back to DVLA. Its better to send the letter with recorded delivery so you have evidence that you have sent the letter.